Questions about which GPS is used

This might be off topic for the alpha release thread. Feel free to move it. Fom my experience so far I don’t understand if you have control over which GPS is used. Once pairing to the android app, you are stuck with the phones GPS? If the phone is off or out of range the device uses or reports what for location? If you don’t pair with a phone and do everything through espflasher\meshtastic\python-web, it uses onboard GPS? I’ve seen that you can specify a static GPS location which is helpful for router mode. What other control is there? My elevation and GPS has varied by 200m and 1000ft respectively and there is no indication in the app what sensor was used.