A ton of wi-fi access points (most?) along with their locations are listed somewhere. Google had a big scandal over this some years back as, while the streetview cars drove around making streetview images, they were also surreptitiously hoovering up the names of WiFi APs. Their defense at the time was that they did it to “improve location accuracy” for end-users. (They weren’t technically wrong - but also, folks didn’t like having their WiFi APs in Google’s databases.) AFAIK, they still do this stuff, not (only) with their cars, but by hijacking every end user’s device to do the war-driving for them, keeping this massive trove of devices and their locations up-to-date in near-realtime.
There are also community-driven projects like wigle.net. That particular site has a surprisingly large number of devices for how small of a project it is. They have an app on f-droid allowing any user to war-drive for WiFi, Bluetooth, even cell towers, and optionally contribute to its public map.
A ton of wi-fi access points (most?) along with their locations are listed somewhere. Google had a big scandal over this some years back as, while the streetview cars drove around making streetview images, they were also surreptitiously hoovering up the names of WiFi APs. Their defense at the time was that they did it to “improve location accuracy” for end-users. (They weren’t technically wrong - but also, folks didn’t like having their WiFi APs in Google’s databases.) AFAIK, they still do this stuff, not (only) with their cars, but by hijacking every end user’s device to do the war-driving for them, keeping this massive trove of devices and their locations up-to-date in near-realtime.
There are also community-driven projects like wigle.net. That particular site has a surprisingly large number of devices for how small of a project it is. They have an app on f-droid allowing any user to war-drive for WiFi, Bluetooth, even cell towers, and optionally contribute to its public map.