I have a Miyoo Mini Plus, and these homebrew/Game Jam Games are really perfect for it.

I've been playing a pokemon Rom hack called Lazarus, and it feels like a fully featured, modern pokemon game, in a GBA style, without just aping Gen 3 assets. It's a delight to play!

Same with Pico8 games. Getting pico8 to run natively on the Miyoo mini is pretty easy, and there are a ton of really cool, bite-sized little games available for free. A lot of them remind me of old flash games, in their simplicity.