I think it would be really cool to displace the reliance upon Fedbook and similar closed platforms to create a Lemmy instance that offers this.

It would require a core group to establish though.

You could either start it with a group that does something like a produce exchange or labour exchange, or you could start it in a big city like New York or London.

You need a core group to get momentum and to reach critical mass, so if you tried to start it in a small city you would either struggle to get any uptake or it might kick off but it probably wouldn't grow beyond that little niche that you carved out.

It's also important to strike a fine balance between offering enough specificity without having a desolate wasteland where there's a thousand different comms, each inhabited with one or two users sitting quitely by themselves.