Here is what I want help with. I'm in the scratch process of this. I want to develop an Android app

Concept: This app works between 2 people. Person A and person B. Person B is travelling to Person A's location. This app should allow Person A to monitor Person B's location (via maps and of course through consent).

How can this be done? I know some sort of backend must be used (thinking Firebase), but I have no clue otherwise.