Remember to turn off wifi access points if your ever likely to be raided by feds, no point guving away your location.
Or tannerite filled manequins on roombas running set routes and wifi access points on.
The choice is yours....
Discussion
Wifi motion detection is a thing, but I doubt it's limited to just AP. Even as that marketing picture suggests I would guess it's any wifi transmitter, clients too.
But in any case, the processing must still be done. Perhaps someone will make a detector on an esp32.
The router I suspect is used because it can more easily connect to servers to do things like this:
https://vpnoverview.com/news/wifi-routers-used-to-produce-3d-images-of-humans/
💯
We were doing this in the 90's with various rf frequencies.
But yes the host processing was the key.
White noise emf generators with a random freq sweeps and power outputs were useful in limitimg the capture of good info.
Also a good deterent for audio bugs....