Lemmy.ml, the most popular instance fo Lemmy out there, is not accessible in my country unless I use a VPN. But, I can subscribe to any community that exists on lemmy.ml from here and even post on those communities from this account.
I love this aspect of Lemmy.
No, it wouldn’t. The Beehaw server is located in the United States. External communities aren’t retrieved via your machine, but via their server.