So long as they only connect to your relay, they only see each others messages and content.
Primal also makes video and content sharing easy over Nostr.
Like, i’m thinking photo album sharing (twitter-like makes photos ephemeral, quickly disappearing on the timeline) and conversation (twitter threading has never been strong imo).
And as long as there is a docker container, i don’t really care what language it’s written in, tbh - tho that is sometimes useful as a signal of the code quality or other aspects
As for actually doing this... running a PDS and relay isn't that hard, and the red dwarf web client is online and can be configured to point to whatever appview you want. There's significantly less experience running your own appview, but there are options & folks are happy to help.
I no longer recommend ATProto, in part because the public by default was a terrible choice. People prefer privacy, not anyone in the world able to read all of their activity. Bolting permissioned buckets on after the fact is not the way, it needs to be core to the protocol design.
Example: https://freecities.app
Video demos: https://vimeo.com/1141492621/23e8b84b8b
Disclaimer: I built it. Lovingly, over 15+ years.