Hashtags might be the closest thing? I know there was a book club here a while back. Not entirely sure how they organised

The hashtags are your closest bet to that.

Pathos.place has country centered discussion. We can use the same spec to build topical discussion. Which topics you interested in?

Not really, people have tried to make a Reddit style app, with limited success. I’m not sure there are enough people here to really have a vast array of topic discussions yet. Jumble has a relay selector that acts like a community feed. On nostr:npub1xxdd8eusvdxmaph3fkuu9x2mymhrcc3ghe2l38zv0l4f4nq...

So far noster is closest to twitter (without the censorship.. I don't think specific groups were a thing on twitter, mostly just hashtag groups. Like has been said, our participation rate is a bit to low to wall off sections at this time. I don't see why something like that could be done though.....

Quoted my response

at the moment, flotilla, jumble, nostr.ble and chachi are the closest to creating communities

Yes, it's built into Amethyst app.

They kinda did although more reddit style. Problem is almost no client supports it.

I just recalled nostr:nprofile1qqs9ajjs5p904ml92evlkayppdpx2n3zdrq6ejnw2wqphxrzmd62swsprfmhxue69uhkummnw3ezuatnv4kx2umnwd5xjapwvdhszyrhwden5te0dehhxarj9emkjmn9wwlr24 has a groups feature with a few NIP variations that may suit your need https://blossom.primal.net/fcaabbb4eac72ecee7bb649190007ff8dd1...