Yah, potential privacy nightmare, but super useful. A quick look on Ali turned this up, which uses ESPHome (open source) firmware for < $AU50. As long as it's in an internet disconnected IoT WLAN network (you do have one of those, right?) I see little risk. The risk will come with phone app enabled crapware versions that are incoming right now I expect.

I actually have a 24Ghz version waiting to be connected to an ESP32 in my to be done drawer, but I may well leapfrog it and grab this instead.