How to Choose Between OnionOS and MinUI on Miyoo Mini Plus (2026)

Ben Rawlinson — Founder & Editor, RetroInHand

Last updated: June 2026

The Miyoo Mini Plus remains one of the most popular sub-£80 handhelds in the UK, and almost no owner runs it on the stock firmware for long. Two custom firmwares dominate the conversation: OnionOS, the feature-packed community favourite, and MinUI, the deliberately minimal alternative built around speed and simplicity. Both are free, both are well-maintained heading into 2026, and both transform the device — but in very different directions.

Choosing between them is not really a question of which is “better” in the abstract. It is a question of how you actually play. If you want box art, save states on every emulator, themes, a music player and pause menus with cheat support, OnionOS is built for you. If you want the device to boot in roughly four seconds, never crash, and feel like a polished consumer product with the absolute minimum of menus, MinUI is built for you.

This guide walks through the practical differences, what you need to install each one, the step-by-step setup, the common pitfalls UK buyers run into (microSD cards being the big one), and how to decide which firmware genuinely matches your habits. Versions referenced are OnionOS v4.3.x and MinUI 20240803-1 and later, both current as of early 2026.

What You Need Before You Start

Both firmwares run on the same hardware and have very similar prerequisites. Get these sorted before you touch any zip files — most installation failures trace back to skipping one of them.

A Miyoo Mini Plus (not the original Miyoo Mini — they share some files but have different builds; check the back of the unit if unsure).
A reliable microSD card. 64GB or 128GB is the sweet spot. SanDisk Ultra and Samsung EVO Plus are the cards owners most commonly report working without issues. Avoid unbranded cards from marketplaces — they are the single biggest cause of “stuck on boot logo” complaints.
A microSD card reader for your PC or Mac.
A formatting tool. On Windows, use the official SD Card Formatter from the SD Association. On macOS, Disk Utility works but you must select the physical card, not the partition.
An archive tool capable of handling .7z files (7-Zip on Windows, Keka on macOS).
Your own legally-obtained ROMs and BIOS files. Neither firmware ships with games, and we won’t tell you where to find them.

Back up anything important on your current SD card first. Both installations wipe the card.

OnionOS at a Glance

OnionOS is the feature-rich option. It is essentially a heavily customised RetroArch front-end with a custom launcher, theme engine, and a deep settings menu accessible via the in-game pause shortcut (MENU + SELECT by default).

What you get out of the box:

Box art and metadata scraping support.
Per-system save states, rewind, fast-forward and cheat support.
A built-in music player and retro-styled themes.
Game Boy Advance, PS1, Neo Geo, Sega CD and arcade systems all configured.
An “Expert” pack with extra emulators and tools.

The cost is complexity. There are a lot of menus. First boot takes longer. The pause menu has tabs within tabs. None of this is bad — it just means you will spend an afternoon getting comfortable with it.

MinUI at a Glance

MinUI is the opposite philosophy. Created by developer Shaun Inman, it strips the device down to a single flat list of systems, a single flat list of games, and almost no settings. There are no themes. There is no scraper. There is no music player.

What you do get:

Boot times of around four to six seconds.
Automatic in-game save and resume — close the lid (or hold POWER), reopen, and you are exactly where you left off, on any system.
A consistent, predictable interface across every emulator.
Genuinely excellent battery life because the UI does almost nothing.
Rock-solid stability — owners commonly report it never crashing.

The trade-off is that MinUI is missing things some people consider essential: no box art, limited cheat support, no rewind in older versions, and fewer per-emulator settings. It is a tool for people who want to play, not configure.

Installing OnionOS: Step by Step

Download the latest stable OnionOS release from the official GitHub repository (search “OnionUI Onion releases”). Grab the full .7z, not the update-only file, for a clean install.
Insert your microSD card into your PC and format it as FAT32 with a 32KB allocation unit size. Use SD Card Formatter on Windows for best results.
Extract the entire contents of the OnionOS .7z directly onto the root of the SD card. You should see folders like .tmp_update, App, BIOS, Emu, Roms and Saves at the top level.
Copy your BIOS files into the BIOS folder. PS1 in particular needs scph5500.bin, scph5501.bin and scph5502.bin for best compatibility.
Copy your ROMs into the matching subfolders inside Roms — for example Roms/GBA for Game Boy Advance.
Safely eject the card, insert it into a powered-off Miyoo Mini Plus, and power on.
The first boot runs the OnionOS installer. This takes around three to five minutes and the screen will appear to do nothing for stretches. Do not power off. When it finishes, the device reboots into the new launcher.
Use the Package Manager (in Apps) to enable any extra emulators you want, such as the Expert pack.

That’s it. From here you can explore themes, scraping and per-game options at your leisure.

Installing MinUI: Step by Step

Download the latest MinUI release for the Miyoo Mini Plus from Shaun Inman’s GitHub. Make sure the file name contains MMP — the original Miyoo Mini build will not boot on the Plus.
Format your microSD card as FAT32, exactly as for OnionOS.
Extract the MinUI zip and copy its contents to the root of the card. You will see a small set of folders including Bios, Roms and Saves — far fewer than OnionOS.
Place your BIOS files in Bios using the folder structure shown in the included readme (each system has its own subfolder).
Drop ROMs into the matching system folders under Roms.
Eject, insert into the device, power on. First boot takes under a minute and there is no lengthy installer.
You’re done. There is genuinely nothing else to configure.

How They Compare in Daily Use

Performance and Battery

Both firmwares run the same emulators under the hood (RetroArch cores in OnionOS, standalone or RetroArch cores in MinUI). Raw performance for GBA, SNES, Mega Drive and PS1 is effectively identical.

Battery life is where they diverge. MinUI’s minimal UI and aggressive sleep behaviour mean owners commonly report 8–10 hours per charge, versus 6–8 hours on OnionOS with default settings. If you commute and need a week of train commutes between charges, that matters.

Resume and Save States

MinUI’s automatic resume is the single feature that converts the most OnionOS users. Press POWER, the device sleeps. Press it again, you are back in the game instantly, even after a full shutdown. OnionOS supports save states everywhere, but you have to create them deliberately with MENU + R1.

Customisation

OnionOS wins here without much argument. Themes, custom backgrounds, box art, scraping, music while browsing, per-game shader settings — all built in. MinUI does not pretend to compete on this front.

Updates and Maintenance

OnionOS updates more often and patches bugs aggressively. MinUI updates rarely because there is less to break. Both maintainers are still actively shipping releases in 2026.

Common Pitfalls and Troubleshooting

Device Stuck on Boot Logo

Almost always a microSD card problem. Either the card is counterfeit, the wrong format, or the files were copied while the card was still mounted incorrectly. Reformat with SD Card Formatter and try again. If you bought the card from a non-reputable seller, try a known-good SanDisk or Samsung card from a UK retailer.

PS1 Games Crash or Show a Black Screen

Missing or incorrectly named BIOS files. Check the filenames are lowercase and match exactly what the firmware expects. Multi-disc games need to be in the right format too — .chd is the most reliable for both firmwares.

OnionOS First Boot “Hangs”

It usually isn’t hanging. The installer can sit on a blank or near-blank screen for several minutes. Leave it for at least ten minutes before assuming failure.

MinUI Doesn’t Show My Games

MinUI is strict about folder names. Each system folder must match its expected tag exactly (for example Game Boy Advance (GBA)). Check the readme that ships with your version.

Both Firmwares: Slow Browsing With Lots of ROMs

Folders with thousands of files slow the launcher down on either firmware. Split large libraries into subfolders by letter or genre.

Practical Tips

Keep two SD cards. They are cheap. Run OnionOS on one and MinUI on the other, swap based on mood. This is the single best piece of advice owners give newcomers.
Back up your Saves folder regularly. Copy it to your PC every couple of weeks. Both firmwares store saves on the SD card and a corrupted card means lost progress.
Use .chd for disc-based games. Smaller file size and better compatibility than .bin/.cue across both firmwares.
Set a sensible brightness. The Miyoo Mini Plus screen is bright. Dropping from full to around 60% on OnionOS can add an hour or more to battery life.
If you’re new to the device, start with OnionOS. The learning curve is steeper but it teaches you what the device is capable of. You can always switch to MinUI later if you decide you want less.

So Which One Should You Pick?

Pick OnionOS if you want a full retro handheld experience with themes, scraping, cheats, save states and the flexibility to tweak everything. Most UK buyers end up here, and for good reason — the polish and feature depth are remarkable for a free community project.

Pick MinUI if you want the Miyoo Mini Plus to behave like a Game Boy: pick it up, play, put it down, pick it up again tomorrow exactly where you left off. No menus, no fuss, longer battery life, near-zero crashes.

There is no wrong answer. Both are excellent. The mistake is committing to one without trying the other.

Frequently Asked Questions

Can I switch between OnionOS and MinUI without losing my saves?

Not directly — the two firmwares use different save folder structures and naming conventions. You can manually copy save files between them for some emulators, but it is fiddly. The easiest approach is to keep two SD cards.

Will installing custom firmware void my warranty?

It does not modify the hardware and the original firmware can be restored by reflashing a stock SD card image, but Miyoo’s official position on warranty is vague. UK consumer rights still cover hardware faults regardless.

Which firmware is better for Game Boy Advance?

Performance is essentially identical — both use mGBA. OnionOS gives you more per-game settings; MinUI gives you instant resume. For pure GBA play, MinUI is hard to beat.

Does either firmware support PS1 properly?

Yes. Both run PicoDrive and PCSX ReARMed cores well. You need the correct BIOS files in either case. OnionOS makes per-game tweaks easier if a specific title needs adjustment.

Can I install both at once and dual-boot?

No. The Miyoo Mini Plus boots from whatever firmware is on the inserted SD card. Dual-booting in the traditional sense is not supported, which is why most owners use two cards.

How often do these firmwares get updates in 2026?

OnionOS sees minor updates every few months. MinUI updates less often because its scope is deliberately small. Both projects are active on GitHub.

Is the original Miyoo Mini still supported?

Yes, both firmwares have separate builds for the original Miyoo Mini. Make sure you download the build that matches your hardware — the Plus and the original are not cross-compatible.

Do I need to update the stock firmware before installing OnionOS or MinUI?

Not usually. Both firmwares run from the SD card without touching the internal stock firmware. The exception is very early Miyoo Mini Plus units shipped in 2023, where a one-time stock firmware update is recommended before installing OnionOS.

What to Read Next

If you’re still weighing up whether the Miyoo Mini Plus is the right handheld for you, or planning your next purchase, these will help:

Best Retro Handheld Starter Kit Under £100 UK (2026) — a full breakdown of what to buy alongside the device, including SD cards that actually work.
Trimui Brick Review: A True Game Boy Micro Successor for 2026 UK? — the closest direct competitor to the Miyoo Mini Plus, with a very different software approach.
Setup & Emulation Guide Hub — every other firmware, BIOS and configuration guide on the site in one place.

The Miyoo Mini Plus is a remarkable device precisely because the community keeps it interesting. Whichever firmware you choose, you’re using a £50–£70 handheld that plays nearly everything from the 8-bit and 16-bit era flawlessly — and that’s a genuinely good place to be in 2026.

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This article was produced with AI assistance and reviewed by the editor. See our Editorial Standards.