I don't quite understand: Instead of using the phones GPS to let me simply chat with people around me, which would be great during traveling or commute, I need to choose the place I chat at?

This seems super counter productive in my opinion. It creates way more friction that I want.

Maybe I want to save a location I have been to as a chatroom, sure but my primary interest would be to have my location determine the chat. So if I enter a university building: boom university chat. I enter Cern: boom Cern chat.

The hard part would be to not just use rectangles but actually make the shapes meaningful. I don't want to walk past a high school or live next to one and then be included in that chat. So yeah. Tricky