Thank you for sharing this
I already looked into audio stem splitting and I made a port for Spleeter by Deezer into kotlin, however Iāve scraped the idea since it would blow up the size of the app to 350MB ish, also I donāt want to rely on online APIs.
I also had something in mind like your second idea but this would indeed take a lot of time and UI/UX design which Iām not skilled at, so for the time being Iām not planning on introducing that.