Just confirming, you’re putting the file named pico-8_0.1.12c2_raspi.zip in the ~/games/PICO-8 directory?
Mine is a 6.1MB file. I bought it in a humble bundle once upon a time. Is yours a legit one?
Also try and run the PICO-8 app without anything in the games directory. I find that the first time, it will just give a black screen, then return to the launcher; possibly initialising itself. Afterwards, run it again. It should have a screen telling you to download the pick 8 files. Transfer the files after this, then run it again.
Here’s a screen cap of where I have it placed, and the expected file output.
