A few years ago I used an RTL-SDR to determine if I had a water leak since my meter is one that broadcasts over 900mhz (iirc). I wrote a small program to parse RTL-AMR output into Prometheus metrics (real life gauges are just like Prometheus gauges, who would've thought) and tracked it over a week while I was away on vacation. No leak luckily.

RTL-AMR: https://github.com/bemasher/rtlamr

Cool!