I lost the link but the research was done by: Douglas J. Leith, School of Computer Science & Statistics, Trinity College Dublin, Ireland, 25th March, 2021 in a paper titled “Mobile Handset Privacy: Measuring The Data iOS and Android Send to Apple And Google”.
Every Android device owner is a Google spy. Every iOS device owner is an Apple spy. They don’t know it, generally. Android and iOS devices constantly¹ harvest the radio data of their surroundings and they send the data home to their respective mothership. This is hard-wired into the platforms and has nothing todo with accounts. An arbitrary person randomly walks/drives by your house with their iPhone or android powered on, and it collects your SSID, MAC, GPS position, etc and sends it to Google or Apple, unwittingly, because people are oblivious as to what’s going on.
¹ The phone user may need to have location services enabled for the phoning-home to occur.. not sure if turning on location services enables the data sharing in both directions or just one. Guess I need to re-read the research.