I am looking to geofence a specific area using Firebase to do things like send alerts to users within a specific area, or perhaps even when they enter an area. I see geosearching capabilities native to Firebase like this, but I'm not sure that it gives me a true "geofence" solution. Furthermore, it seems like it only allows me to define areas in the shape of a rectangle, I need to geofence using custom polygons.
Any advice on how to best utilize Firebase or other systems for this?