>What is the typical viewer experience?

Think it depends a lot on the type of stream. The vibes are all over the place. Say gaming stream, live walking stream vs a talking stream vs a podcast stream.

Size of the stream also matters. If you're regularly in the comments of a 50 person stream commentators recognise each other and there is interaction not entirely unlike old school forums that have regulars. In a 1000+ stream nope.

So I don't think there is such a thing as a typical experience.

The main one I follow is a talking stream of someone I've been following for years. So has a bit of old friend vibe in that you know a lot about this person & it's a comforting presence. But of course its all parasocial and one direction only (mostly) so old friend parallel is kinda fake.