Thank you! Not too much really. I "ported" it to the SparkFun arduino core - which mostly involved adding some ifdefs and fixing a few bugs, like this one https://github.com/sparkfun/Arduino_Apollo3/issues/478 , and added the adafruit sharp memory display library which integrated quite well with the existing graphics support. Then I wrote an interrupt routine to scan the keyboard.

I also had to add some error handling patches which someone had shared in the ulisp forum (because you don't want the REPL to crash if you have a typo)

Working with uLisp is fun - it's not super fast and it does have a few limitations and gotchas, but it was by far the easiest option for this project as so much was already supported. And the documentation and community is very nice.