Managed to get a Pure Data patch running in an Android app. Their lib is nice and seems actively maintained. Need to target an older Android version though, some maintenance to do (actually it's a one-liner, a PendingIntent needs a mutable/immutable flag, I might have a go at contributing)
This is going to be awesome
This'll work, the Pd patch is very basic at the moment so there's some pops and clicks, easily fixed:
https://www.youtube.com/shorts/0Zk6rc8JqIE
YouTubeEliminated the pops and clicks. Also implemented midi support, so this should be able to drive any synth. Next to add note editing, visitor size/range, and patch loading and saving.
I reused that volume control I invested a load of time in. Almost works without too much thought, just needs a little tidying up.