Is there a setting anywhere for moderators to take a community private (to make the posts, comments and other data visible only for people who are subscribed)?
If so, how does the mechanism work for finding and/or subscribing to private communities?
I’m guessing that’s not really possible by design, since a subscriber from a remote instance automatically means their instance has to mirror all content from your community. It’s not possible (AFAIK) to make a community available to just one user of a remote instance; at least the admin will always see the mirrored content.
Aside from that, it’s also not possible to authenticate a remote user.
I think if a remote user can moderate a community, there’s probably a way for a private communities to eventually be a thing.
Exactly. The mechanisms needed to implement it are there, but I don’t think the devs are interested in much more than making it more stable and robust right now.