Account creation / joining communities from elsewhere?

I just tried to create an account, JoeGermuska but got an error that the username was in use.

Today is the first I've heard of PieFed but before I tried to make that, I joined the meta community as https://midwest.social/u/JoeGermuska -- I wonder if that had anything to do with it?

Also, while my subscription from that account is no longer pending, there are no posts showing. But it's only been 5-10 minutes so maybe that's just how federation works?