@Gargron @gwynnion I really think it might have been the official app, but I can't say for certain, and I don't want to lead you astray.

What I remember is that although it supported multiple accounts, it had trouble switching from one to another. Two accounts it could manage; when I added a third, it would crash every time I tried to switch. It was a Moto G4 Play; don't remember which Android OS.