Comment by plorg

Lots of incomplete answers - you can maybe probably follow anyone you want from any decent server. But servers block each other for a number of reasons, so for good or bad you probably want to just pick one, see if it works, and if there are people you can't reach you'll need to find another. It's possible to migrate to a different server in a relatively seamless way. From what I can tell choosibg a server is based a lot on word of mouth. Which I assume is difficult if the site you're using explicitly forbids discussion of Mastodon.