Android Question Google maps real time location

You can use FireGeo to store the Location for each Device you want to track.
On app start get all Devices you want to track, put them in a global list and create a custom icon for a marker on googlemaps...

You then set a listener for each device... On Locationupdate of a Device you update the Marker-Position on googleMaps...

There is NO READY Example on this. You need to build this solution by yourself.

PD: Please note that the lib uses Firebase Realtime Database for this.
Also note that with the free plan you maybe get fast to the limit of the free plan based on the DatabaseTraffic your devices are creating on each update....