I made a 2 button version of my Pico 8 fanmade handheld. It works better than the 4 button version so I’ll focus more on just the 2 button version.
I also made it possible to boot into Pico 8 using cartridges. They aren’t rom cartridges, but SD cards with a 3D printable shell to make them look and feel like cartridges. The designs are not final. It works and I posted a guide on the Pico 8 forums: https://www.lexaloffle.com/bbs/?tid=44530
You can find the SD card ‘cartridge’ files on my Thingiverse: https://www.thingiverse.com/thing:4950864
How does this all work? You plug in a SD card into a USB SD card reader that is connected to a Raspberry Pi and have the Raspberry Pi search for a Pico 8 .p8.png file in the SD card or anything else you want it to find. If it finds a Pico 8 rom file, it will run that game in Pico 8. If it finds nothing, it will just boot into Pico 8 with splore. You can use this for any project you want, not just Pico 8. Here is a picture of version 2 of my handheld:
Raspberry Pi TV console project
This is my new project. It is not Pico 8 specific, you can use this for any project you want. I will use the same SD card cartridges in my Pico 8 handheld project in this project too. You can use this as a Pico 8 specific console, or use other fantasy consoles that run on the Pi, or anything else you want. I tried soldering a old RCA cable to a Raspberry Pi Zero and it works, so I will make sure this project will work on CRT TVs.