Looks neat! I like that you show how many are in range. Here's some suggestions, take them for what they are worth.

- Fix the layout on iOS Safari.

- Show the location of all current users (with opt out) on a globe. Users can see where the activity is and who is chatting where.

- Consider adding ignore to squelch certain users.

- Show past messages for your area.

- Add voice messages and autoplay (with opt out)