Hi,
I just released my noisy side-project, the Amigo Tracker. It plays 4 channel ProTracker modules from local storage. Hope you find it as fun as I did making it 
Thanks, I had to write the whole thing from scratch as there wasn't anything suitable out there.
Timing has been a pain, but at least everything finally sounds like music. That said, I'm pretty sure my implementation of MOD "tempo" is still wrong 
What comes to the actual code, I have 1 looping and 4 one-shot sampleplayers per channel so that I can sort of blend the sounds together like an actual Paula chip would. Other than that I just use lots of precalculated values and avoid divisions. I also intentionally chose to only implement .mods as they only have 4 channels and a very low samping rate.
According to the stats the app runs at 400+ fps when playing, meaning the player should be light enough to be in a game. At least that has been my plan from the beginning. You can already find the modplayer asset on itch: Playdate MOD player by Outgunned Games
The lib works great in game with GC turned off. Not so much with the default settings 