Scientists in Germany have demonstrated a startling new form of surveillance: identifying people using nothing more than ordinary WiFi signals. By analyzing how radio waves bounce around a room, researchers can effectively “see” and recognize individuals — even if they are not carrying a device and even if their phone is turned off.
A paper from around a decade ago talked about using WiFi to identify key strokes so with large data models we have today I would assume they could get pretty good fidelity on a person. Maybe not enough for “beyond a reasonable doubt” but probably enough where your WiFi company is selling your data on what you do at home