Whatever companies publish/republish nowadays as ROMs or that include ROMs. Plenty of homebrews, specially on Itchio, and some times (albeit rarely) we get stuff from companies like Capcom, Atari and Konami. It’s always nice when that happens.

For handhelds, I have a Supaboy, a PSP, a PS Vita, a 3DS old, a New 3DS XL and a Switch.
Out of those, the Switch is the only one I can’t play emulated games or homebrews, given I haven’t modded it nor there is flashcarts for it.
And among the ones we both have, the 3DS XL models seem like the best ones. Not very heavy while still being decently sized, good resolution and color palette, buttons with good pressure, and for emulating Nintendo games, Nintendo’s own devices are usually the best for their given release period.

There are also games sold/distributed only as ROMs you can run on emulators, if you’d be interested too.

I’m seldom picky about what I play, so, by extension, expect to see little to no consistency in what I’d recommend:

#hasicontent 8Doors: Arum’s Afterlife Adventure A Vampyre Story ABZÛ Atari Vault Batman: Arkham Asylum Game of the Year Edition Batman: Arkham City - Game of the Year Edition Battle Chef Brigade Deluxe BlazBlue: Continuum Shift Extended Bloodstained: Curse of the Moon Bunny Swordmaster Story Catherine Classic Celeste Celeste Classic Celeste Classic 2 Child of Light Dandara: Trials of Fear Edition Devil May Cry 4 Devil May Cry HD Collection Downwell Dreaming Sarah Dusk Child Dust: An Elysian Tail Etherborn Final Fantasy VI Final Fantasy VII FINAL FANTASY X/X-2 HD Remaster Final Fantasy XII The Zodiac Age Grey-Box Testing GundeadliGne Gundemonium Recollection Hitogata Happa Injustice: Gods Among Us Ultimate Edition Ittle Dew Kimmy Kitsune Zero Knight Club LiEat Mary Skelter 2 & Mary Skelter: Nightmares (revamped & retconed version; included as an unlockable in Mary Skelter 2) Mary Skelter: Nightmares (OG version; still being sold) Metal Slug Metal Slug 3 Micro Mages Minecraft Minoria Mobile Light Force (aka Gunbird) Moero Chronicle Momodora Momodora II Momodora III Momodora: Reverie Under The Moonlight Ni no Kuni: Wrath of the White Witch No More Heroes No More Heroes 2: Desperate Struggle Okami One Strike Phoenotopia (Adobe Flash version; didn’t play the remake yet) Portal Rabi-Ribi Remember Me Riddled Corpses Saints Row: The Third Senran Kagura Bon Appétit Shantae and the Pirate’s Curse Shantae: Half-Genie Hero Slay the Spire Slipways Classic Songs for a Hero: Definitive Edition (“A Lenda do Herói - Edição Definitiva” in its Portuguese name) Starbound Super Dungeon Boy Tanglewood The Corruption Within The Deed Unparallel Va-11 Hall-A: Cyberpunk Bartender Action Wake Up Wishing Sarah Wonder Boy in Monster World | Wonder Boy V: Monster World III World of Final Fantasy コテ・DE・メクール 真・魔王ゴルベリアス　先取り横スクロール面

A Vampyre Story worked nice on Wine on an old computer with Mint Xfce when I played it last year. Only had to set Wine as windowed full screen, since the game got issues when alt-tabbing. Also worth noting it requires DirectX on Windows, so you’ll have to use DXVK.

Haven’t seen any PICO-8 games lag on Linux, and both Celeste Classic games were released on PICO-8.

Dust: An Elysian Tail might be playable, bar maybe two areas (one mandatory) that have a lot going on.

Slay the Spire should run fine, but I had to sideload an older version of OpenJDK to get it working (maybe 8 or 11; don’t remember which exactly).

Songs for A Hero also seems to run fine.

Tanglewood is a Mega Drive homebrew, so should be playable on any emulators your PC can run.

Va-11 Hall-A: Cyberpunk Bartender Action also runs fine.

Böbl and Nix: The Paradox Relic should both run fine on NES emulators.

Mint 21.1 Xfce, and if Android counts, ArrowOS 13 (on phone) and BlissOS (on an old computer)