This reminds me a lot of radio.garden - very cool!
bitchat now has regional chat, using geohashes and nostr (kind 20000). in TestFlight. https://github.com/permissionlesstech/bitchat/releases/tag/v1.3.0
Discussion
It reminds me of the old app Yik Yak. Loved that you could be in a crowd watching a speaker and be having a conversation parallel with other audience members about what the speaker was saying, unknown to them and without their permission