I spent a fun day installing the 6/20 Disco image to emmc, fixing niggles like polkit-1, and installing the knossos launcher for Freespace Open & mods (hard-light.net). I'm glad to say the game runs very well on the APi. Storage space was an issue, so I made my sd card executable by adding a line to /etc/fstab:
/dev/disk/by-uuid/1234-5678 /media/sdcard vfat nofail,exec,dmask=000,fmask=000,gid=atomicpi,errors=remount-ro 0 0
Not sure all that is needed but it took hours of trial and error, and frequent use of a recovery USB drive, to get things working so I'm disinclined to change it now.
Then, when running knossos for the first time, I set the install directory to /media/sdcard/games/... Good old-school alien pew-pewing fun.
P.S. I printed a case for the APi. It's written in Openscad, so
easy to modify. Files here:
P.P.S. Replace 1234-5678 with the UUID of your sd card. (sudo blkid and look for /dev/sda1)