I don't want my ISP doing this to me, but it sounds like something pretty cool to do myself. Does anybody know what the current state of "self-hosting" this kind of functionality is?
None of the above.
The setup process has you select 3 reference devices. You should pick the devices so that your normal motion areas are between the device and the router.
The router then watches the WiFi signals from those devices. If they fluctuate more than baseline, it's assumed that something is moving around in the area.
It's a threshold detection that can serve as a crude motion sensor for home/away purposes.
Why? It's already there and reliable.
They can also be programmed to detect people on the floor, so if you have elderly in your house you can know if someone fell, without cameras. They are made for hospitals but are cheap, but not 100% accurate for HR and falls, but reliable enough for security, and cheap.
Wifi is something most people already have available, and requires no new wiring or battery management. That's the selling point.
Interesting, mind sharing links to these?
I found a GitHub repo for "ESP32-CSI-Tool" that seems related to Wi-Fi Sensing, but zero references to "FreqSense" in the Wi-Fi/RF context.
The only FreqSense I found is an obscure academic paper on speech recognition that doesn't involve any form of hardware.