I read the referenced papers : https://atap.google.com/soli/technology/

About 60Ghz technology : https://www.embedded.com/why-60ghz-mmwave-is-moving-into-the...

I've played with some 6Ghz 2$ microwave radar sensor and Software Defined Radios though I have not yet used 60Ghz.

Electromagnetic Waves are kind of magic when used in not conventional ways. I remember seeing the 2015 disney EM-sense video https://www.youtube.com/watch?v=fpKDNle6ia4 which is a non-radar way to listen to the environment.

I mean, in theory you setup 3 WiFi base stations and you can use WiFi in roughly the same way. No where near as accurate, of course, but you can easily figure out which areas of the house a person is in.

I don't see why this wouldn't be an even better way to do the same thing.