

In the sense of multiple users in Android settings? That works, it can be enabled in settings -> system -> multiple users. I haven’t tested it though, as I don’t have any need for that.
I use Microsoft Authenticator and Microsoft Outlook for work, and both work flawlessly with /e/OS. Thankfully I have not had any reason to test Teams, but I’m pretty sure that would work as well.
OpenStreetMaps is not an app, just a map. Magic Earth (and Comaps, for that matter) uses OpenStreetMaps.
Personally I never liked Magic Earth. It jumps into navigation mode too easily and I just find the interface to always do something else than I want it to. Personal preference I guess.