I'm all for local nostr, but I think there is a conflict with privacy. Something that can be fixed with more design and some NIPs though, once it's thought through.
Discussion
I designed the algorithm to be privacy preserving, 300km range is cheap < 1min,
50km range tricky ~10min
4m range, good luck
I wished to incentivize at least 1 relay per 300km around the globe, but I think people were busy.