We let anyone use any authentication app. The Microsoft one is the best one. I'm pushing to make us exclusive because I'm sick of the IT support guys trying to support a dozen apps. You don't have to use your Microsoft account provided to use the app or back up your credentials.
I feel like Lemmy is not very active though, unfortunately. Or maybe I'm on the wrong Lemmy and not subscribed to enough communities or whatever they call sublemmies.