Mason is a user on octodon.social. You can follow them or interact with them if you have an account anywhere in the fediverse.
If you don't, you can sign up here.
Not sure what local timeline does exactly. I'm guessing it's not geographically local, but rather users on the same instance?
@Itsamecj Correct. Also, federated timeline is local + other instances' users' messages that have been sent to your instance because at least 1 user is following them, not the Entire Firehose of Toots.
@Itsamecj Indeed. It's one of the weirder parts of gnu social, and it's going to be interesting to see how it plays out this time.
@r4v5 interesting. Still trying to wrap my head around the federation structure, seeing that the 'rules' seems to also depend on each instance's administrator