Thanks.
After some minor yak-shaving, had some success in building some apks provided via:
https://github.com/onyx-intl/OnyxAndroidSample
Not using Android Studio and just doing "./gradlew assembleDebug" from the command line seemed to be fine.
One of the resulting apks was sample(-debug).apk, which contains some pen and stylus related activities. These seemed to work fine on the Max 2.
May be if relevant developers of note-taking apps were pointed at some relevant sample code something decent might result
