The overall support for embedding audio in PDFs is generally quite poor. A PDF with embedded audio cannot be played on an Android device WHY? It cannot be played on a Kindle Fire - again WHY. I have made several PDFs with embedded audio which play in Acrobat (only after a lot of tweaking) - this process should be much easier after all this is 2019 not 1999.
Simple question: what's the point of having educational PDFs if the embed audio cannot be played on an Android?
The world liked PDF, and made PDF apps. The world wasn't interested in multimedia PDFs so most other apps just don't bother.
It's about other people's priorities.
Well... except that Adobe's mobile apps don't do multimedia either. This is pretty hard to understand, but they have long been independent units with their own resources and priorities. In my view they should have focussed on feature parity, but that doesn't seem to have been Adobe's view until very recently (they have helpfully removed features from mobile apps to achieve some sort of parity, not sure if that's progress...)