Thanks for your reply, at least that makes two of us trying to use Peertube. Out of a whole community. It's quite unfathomable to me. 😕
Anyway, not to sound ungrateful, I've been contributing to open source projects for the last 10+ years (not as dev but mostly documentation with close coordination with devs) so I think I know something about the other side of the fence. I like the UBports project, I want it to succeed, and I'm commited to using UT as my main device OS. Still, I am really confused by what I consider obvious blind spots, such as this one and a few others (the whole Telegram thing).
BTW I found a workaround about the full screen issue: in the address bar, change the /watch/ in the url for /embed/.