Ordinary WiFi networks could quietly become powerful surveillance tools, allowing people to be identified without cameras, special sensors, or even carrying a connected device. Researchers showed that unencrypted signals routinely exchanged between WiFi devices and routers can be used to create radio-based images of people and recognize them within seconds. In tests involving 197 participants, the system identified individuals with nearly 100% accuracy, even from different angles and regardless of how they walked.
ML models trained for a specific task are not necessarily inefficient. It’d probably be more efficient to add a single pi or container for “sensing” than adding a dozen physical sensors all over the place.
But it also looks like a new wifi standard will include some non-ML sensing capability on router anyway, but probably won’t be available till the 2030’s. I’d expect the ML approach to have solid options within a couple of years.