Also an android user. For my self hosted instance I gave up on the mobile app. From what I recall it wasn’t possible to get the push notifications without being on a paid teir for discourse because of google api calls or something (there’s topics about this somewhere).
So… instead I’ve started working on a python script which sends a message via Signal when people have an unread notification for more than an hour. 
not great, but better than nothing. I haven’t accounted for chat yet.