Your use-case is a bit novel, so it might be worth asking in our forum to make sure I haven't misunderstood your requirements: https://github.com/supabase/supabase/discussions

I think we have all the pieces in place for you to use:

  - a Postgres database with PostGIS
  - a Realtime listener for listening to database changes

I don't know if you need realtime though if you are constantly sending the user's location to the database. It might look something like this:

  - Turn on PostGIS
  - Create a Postgres function which takes in the user's location and calculates radius results. eg: get_objects(lat text, lng text, radius smallint)
  - Call this function from the client every XX seconds using the client[0] `supabase.rpc('get_objects', { lat, lng, 10 })

Hope that gives you a few ideas!

[0] RPC: https://supabase.io/docs/reference/javascript/rpc