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
Resonance for Android

YouTube
Eliminated 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.
Multitouch! And note selection. All that's left now is patch load/save/crud, and some UI polish, plus a setting to toggle midi mode (which I've not actually tried yet)
I have no idea why yet, but F#4 doesn't produce any sound... it's a bizarre bug.
Improved midi note picker, splitting into octaves makes finding notes much easier than just having a grid with 127 cells.
@oppen our company uses max/rnbo for realtime audio processing. Unfortunately there are some issues on android like some components doesn’t work properly (on android target) I was wondering (from an audio designer perspective) how difficult it would be to use puredata instead of max. Also did you use heavy compiler to compile pd to cpp?
@umurgdk I used libpd for Android: https://github.com/libpd/pd-for-android/ Easy to integrate but needed to target a slightly older Android version due to an internal PendingIntent missing a new mutable/immutable requirement. Might already be fixed in their snapshot releases (they have already fixed the 16Kb alignment Android requirement in a snapshot so they're actively maintaining it)
GitHub - libpd/pd-for-android: Pure Data for Android

Pure Data for Android. Contribute to libpd/pd-for-android development by creating an account on GitHub.

GitHub
@oppen Ooh they already have android jvm bindings, nice! I had to create my own jni bindings for RNBO. I will discuss this with the team, thanks! Btw if I may ask, did you encounter any runtime differences between running the patch in your editor and running it in android project. We have such problems and to be honest no proper way to debug. Sound designers can't reproduce the problem in the editor, and I couldn't find a proper way to debug it in the android app other than logging the outports.
@umurgdk not with a smaller patch doing 'ordinary' things, but a very complex patch that abuses Pd running on a computer did sound different, that in all likelihood is just the poor phone speaker though. I'm just using unadulterated oscillators as sound sources in this app, that oscillating resonance is of course going to challenge little phone speakers too.
@oppen I see, thanks for answering my questions ^.^