If you use a Android device google can track you via scanned and known wifi Networks without any connection! Android scans your area, shops, stores for public wifi networks, via LTE / GSM the OS verify the Data online at Google. As Result Google Maps sends you Popups to VOTE the last visited Places at Google Maps.
That’s all WITHOUT GPS and WIFI connected only LTE/GSM !
Purge Google Account! (disconnect!) and disable all unwanted Google Apps especially Uploaders (Backups) then go Android Settings -> Wifi -> Advanced Wifi Settings!
Disable the „local wifi scan“ option switch at Android!
Remark:
- There’s no guarantee that google or other company’s can re activate it again or run the service as hidden tool!
- No one knows which apps do run this tools at Standby Mode on Background!
- To be safe remove the Battery of the Phones! or put it into a Metalbox (Copper Faraday Cage)