I was looking to automate a shower Extractor Fan as I don’t find the ones with the inbuilt humidity sensor very good.
So: Aqara Humidity sensor placed somewhere in the shower. Near the fan. Occupance sensor. Sonoff switch to trigger the fan.
If the humidity is > than threshold and the occupance sensor is active = turn on fan.
I was looking for a good ZigBee occupancy sensor though , the aqara fp sensor look all wired and not battery operated.
I have this setup, minus the occupancy sensor. Occasionally on really humid days, the fan kicks on by itself, but that is fine.