I think they still need a separate user account. For one thing, a PeerTube channel is 'attributedTo' the user account, in the same way that Lemmy communities are 'attributedTo' the moderators. A Group belongs to at least one Person, it can't belong to itself. Another is that it allows for creators to comment on videos, and either be recognised as the 'OP', or as a fellow content creator.

In terms of rendering things like Likes and Dislikes, it has the info in the backend, so it may as well. They don't Announce votes like Lemmy does, you have to activitely fetch them, so the channel as it exists on PeerTube provides a definitive source. Likewise, there's all sorts of reasons why comments get out of sync, so the channel provides an authoritative place where you should be able to see them all.

There is a friction though. I like the idea of a place that only open to people willing to create content, and isn't interested in signups from 'lurkers', but providing a mobile app doesn't seem compatible with that.