"On most Android devices, Google, as the network location provider, provides a location service called Google Location Services (GLS), known in Android 9 and above as Google Location Accuracy. This service aims to provide a more accurate device location and generally improve location accuracy. Most mobile phones are equipped with GPS, which uses signals from satellites to determine a device’s location – however, with Google Location Services, additional information from nearby Wi-Fi, mobile networks, and device sensors can be collected to determine your device’s location. It does this by periodically collecting location data from your device and using it in an anonymous way to improve location accuracy."
Consider the implications of Google collecting "anonymous" data from billions of Android phones. The technical details of scale, regularity, which sensors, their resolution, etc are highly germane here, but unfortunately not public. This is a very large blind spot in public scrutiny IMHO.
