It's actually sold as a feature on some routers - get an alert when there is movement detected in your house. Another reason to never use the router your ISP gives you.

https://www.xfinity.com/hub/smart-home/wifi-motion

@networkypeople can these wifi7 chips fit in smartphones? does aluminum foil matter in this context? I presume routers with wifi7 will be cheaper because the value of the surveillance will offset the cost, so if its possible to degrade the performance a bit so it cant 'wifi-sense' I'll buy one eventually.

Phones are becoming surveillance devices, wifi routers becoming one, your car gps, alexa, and additionally wherever you go out there are CCTVs capturing you. It's definitely required at some places to maintain security but a widespread and unruly exploitation of privacy does make me feel a little claustrophobic.

We're so cooked.