Actually, with v3, you can follow "any" peertube channel or account regardless of whether your instance does the same or not. Earlier this was only possible with a mastodon/pleroma account only. Now your peertube user account in instance "a" can follow any channel anywhere in the fediverse.
This is like you want to follow some channel from tilvids.com but dont want to follow the entire instance.
yes. you only need an account in one "instance" and you can comment or aggregate videos from any participating instance and comment on the videos as if you had a local account there. Social function is a big deal of activitypub
This is like you want to follow some channel from tilvids.com but dont want to follow the entire instance.