@MaryPot @FediTips @MastodonEngineering As @harald mentioned Hubzilla has groups support. Friendica too. But I think their UX are way to difficult and unpolished to use for most people (my opinion).
So far I think NodeBB forums and Lemmy are the closest you'll get the FB groups experience, but they are still a bit too cumbersome.

@FediTips If I reply to a post from someone who has restricted who can follow them, then who can see my reply?
Is it safe to say that if I create an account somewhere with follow requests restriction turned on and boost all @ mentions I get, then this account will act as a kind of private group on Mastodon?
About groups, is there still any work going on to implement native groups in Mastodon?
@MastodonEngineering #mastodev #activitypub #groups