hmm...yeah that would seem to be one of the next best developments in this space. It would be nice to have topic specific groups somehow. Hashtags are ok but somehow lack the precision a dedicated group with willing participants would have I think
Discussion
There are a couple different approaches that are hopeful, but it's still all very young.
Zap.cooking is becoming a great example of a topic-specific client, melding topic + community, through relays + filtering.
jumble.imwald.eu has Discussions, which are somewhat reddit-like topic based threads, also accessible through flotilla.social . They are a relay-first design, which is helpful to know when navigating through them on imwald and absolutely necessary to know when viewing them in flotilla.
Relay-based private & public chat groups are getting better, too. Chachi.chat is set up to organize multiple types of posts. The main chat is accessible across all other group chat clients, too, like flotilla, so participants aren't tied to one client, for most of the activity.
This stuff is getting better. Part of what's lacking is patient, explorative, maybe less-techie people willing to participate and set up groups & the relays to host them, so this stuff can be improved further.
You're welcome to take a look at one of my example groups, Igneous is Bliss, https://chachi.chat/spatia-arcana.com/oysloughfidr where I talk about rocks, to myself and sometimes a couple other people :)