

I think there are 2 levels here: basic federation, where you can follow a channel on another instance and comment there, is opt-out like the rest of the fediverse. In fact you can even comment from Mastodon. The platform-level following is another thing, that enables other uses.
The issue of search is unrelated to that, it’s the same as with other fediverse platforms: search only searches on the current platform. But peertube also allows you to search on global indexes:
https://docs.joinpeertube.org/use/search#global-search
And, of course, you can use Sepia Search, a curated index of instances by the people behind peertube:






If not hosting anything is ok for you, deltachat allows you to share locations to people in a chat. It’s fully e2ee. You can use it with existing relays, but if you want you can host one that will be useful to everyone: https://chatmail.at/