I've not followed any evolutions in this area, but there's a cool paper from 2014 about using WiFi channel state information to detect 87%(!) of falls in an experimental condition[1]. It's been a while since I read the paper, and I no longer have access, so caveats aplenty, but it's one of those things that pops into my head sometimes and I wonder if it's seen any real-world deployment.

[1] - https://ieeexplore.ieee.org/document/6847948