Ha! You found the pineapple - that's a relic of my initial starter project as I was figuring out a Fennel => Playdate build proces (+ how to make art assets that work) https://github.com/therabidbanana/playdate-fennel-starter/tree/main
Interestingly the Playdate SDK seems to compile images to a custom format since it only allows 3 colors (white/black/nil), so they needed to be sitting in assets with everything else. :D