While this doesn't solve the problem of a general privacy community, the most recent update on this is from 2 days ago, about exploring support for Lemmy
https://meta.discourse.org/t/activitypub-plugin/266794/346
See also this older related thread
https://socialhub.activitypub.rocks/t/lemmy-discourse-federation/4177
If it works, it would open us up to a lot of official communities (PrivacyGuides and Mozilla both use Discourse for example)
I just hope that if/when this is implemented, those other entities have a good experience with activitypub and don't turn it off after a brigade or something