Is there a way to manually change GNSS Networks (Galileo, GLONASS, Navstar, BeiDou) on android? Or at least deactivate a specific one? Maybe with root access?
I briefly checked that the other day and it doesn't seem to be the case. To my knowledge, the GNSS hardware will gather info on all available (supported + reachable) constellations to give the best location estimate.
There are ways to get raw measurements in some devices, but that'd be at the application level so I think it's not what you're looking for.