This is an older article about it from 2018 https://www.vice.com/en/article/a3aaqp/mit-device-uses-wifi-to-see-through-walls-and-track-your-movements
Now there is discussion of the possibilities of using the tech to "capture people’s physiological signals, monitor sleep stages, and recognize emotions without putting any sensors on their bodies" https://cse.engin.umich.edu/event/wireless-systems-that-see-the-invisible-with-machine-learning-through-wall-vision-emotion-recognition-and-health-monitoring