Would love to know if anyone monitors their home or office RF spectrum for unexpected guests, or just for fun.

I’ve played around with hackRF and it seems like that type of scanning is something you might do in highly sensitive environments.

I use https://github.com/merbanan/rtl_433 on the tire pressure monitoring system (TPMS) band used by my car (315 Mhz) to trigger home automation like turning on the lights as we're pulling up. (rtl_433 publishes to MQTT, which triggers actions in Home Assistant for certain serial numbers.)

Side effect is that it also logs the tire serial numbers of most (but not all) cars pulling into my driveway.