Comment by transpute

That's based on UWB (Ultra Wideband), which is also present in some iPhones.

https://staceyoniot.com/two-companies-show-where-our-uwb-fut...

> Outside of fine-grained location tracking, UWB is also used for radar sensing. Google is using UWB for its Soli radar, which is embedded in the most recent Nest Hub display to track respiration during sleep ... Novelda, argues that UWB sensing is more effective than the traditional motion sensors that hotels have historically deployed because they can sense a person even when they are still by “seeing” micromovements made by the person’s breathing. Lenovo embedded the Novelda chip into its laptops as a way to keep the screen on only when a person is in front of it, which helps save on battery power.