Went back to a previously-found project that helps with generating MIDI on Android: android-midi-lib. This is a really easy-to-use library (albeit with code-only documentation) that makes it easy to generate MIDI on Android.

I ended up trying out one of the examples included with the android-midi-lib project in a new Android application called Generate. This application then generated a simple MIDI file that could then be read by my earlier-created prototype of a MIDI playback application.