While radar has been around for decades, research into WiFi doppler imaging was jumpstarted by Intel's release of custom wifi firmware around 2010. A decade and hundreds of research ("device free wireless sensing", "CSI imaging") papers later, there is now open-source code for doing this on sub-$20 devices. In the mid 2000s, similar imaging was used in WoT conflict zones to locate adversary humans by "seeing through walls".
Radio spectrum and devices using that spectrum are managed by national regulators in each country, who can set policy for authorized applications. Until national regulators step up, the only defense against passive through-wall, Wi-Fi Sensing is EMF shielding for the walls, roof and floor of specific areas in homes and businesses. Otherwise, "The Transparent Society" (David Brin) is incoming.
https://lkml.org/lkml/2023/2/12/314
> Intel Visual Sensing Controller (IVSC), codenamed "Clover Falls", is a companion chip designed to provide secure and low power vision capability to IA platforms. The primary use case of IVSC is to bring in context awareness. IVSC interfaces directly with the platform main camera sensor via a CSI-2 link and processes the image data with the embedded AI engine. The detected events are sent over I2C to ISH (Intel Sensor Hub) for additional data fusion from multiple sensors.
https://www.techpowerup.com/276114/new-intel-visual-sensing-...
> The company didn't detail how it goes about this, but technologies already exist to combine visual input from the PC's cameras; radio from the PC's antennas, audio from its mic array; to form a picture of its surroundings.
https://community.intel.com/t5/Blogs/Tech-Innovation/Client/...
> With an initial focus on respiration detection, we hope to extend the technology to detect other physical activities as well. Intel Labs will demonstrate an early prototype of breathing detection ... The solution detects the rhythmic change in CSI due to chest movement during breathing ... The respiration rates gathered by this technology could play an important role in stress detection and other wellness applications.