Google does it I think? At least in some cases, e.g. when multiple devices that are logged into their respective Google accounts are using that IP, and Google

Google does it I think? At least in some cases, e.g. when multiple devices that are logged into their respective Google accounts are using that IP, and Google knows what location those usually reside at when together. I've had Google pop up reliable location results for me, to the granularity of a small town, even if they had no information about me specifically to help them deduce this. It doesn't always happen though.