Miyoo Mini is a miniature handheld video game console based on Linux. You can probably find it for 40$ or even cheaper if you buy it second hand. It's a relatively cheap way into handheld video games.
Miyoo Mini Plus is also awesome. It's slightly larger so possibly more comfortable to hold and use for longer sessions, because larger there's more battery, and it has Wi-Fi for networking. I think you can find it for 80$ or so. That's still fairly cheap, I think.
OnionUI/Onion is an operating system that's made for the Miyoo Mini and Miyoo Mini Plus. In my opinion it's a more solid and user friendly than what's installed out of the box.
It's powerful and simple, it uses RetroArch to emulate a ton of widely used and less known systems. It supports niche systems like the PICO-8, and the FAKE-08. There's a large community and an active development team who write documentation on installation and usage. If you do stumble into issues, someone else has probably done the same, figured out how to solve it, and made the solution available on the internet.
PICO-8 is a fantasy console. It costs about 15$. It's fully digital and supports emulation on many devices, like the Miyoo Mini.
There's a ton of cartridges (carts for short) made for it. That's what PICO-8 call their games, like those old cartridges for Nintendo Entertainment System. What's really nice is that people make new games all the time, and since it's digital, the games are widely accessible on digital store-fronts like Itch.io.
Many cartridges can be found on Itch.io and PICO-8's forum. Many for free, and some costs a tiny bit of money, like 1-3$. There's also catridge collections like CorgiSpace that's available on Steam.
I'll curate a list of awesome little gems of games, and link back here.
