WiFi routers are about to be exploited using standard hardware to track you, even if you're not carrying a device with you!
Uh oh!! I've known about this for a while but now it looks like the cat is out of the bag!
https://www.kit.edu/kit/english/pi_2025_069_the-spy-who-came-in-from-the-wifi-beware-of-radio-network-surveillance.php