alt Hacker NewsGoogle is not using exclusively DBs like MaxMind for geolocation though. They fuse a lot of data together and probably can even discern which building you're on from the other local network devices without the precise geolocation sharing.
Like the Meta/Yandex apps were doing, just not strictly for position tracking, but more centered toward pinpointing your unique id.
As I understand it, this tag might be at some point be supported by non-Google browsers as well, without access to Google internal databases. At first probably the Chromium-derived ones, which this tag probably lands up at some point.