OK, for fans, see the community FAQ. (It says Alexa in the thread title, but it applies whether you are using a voice assistant or not.
FAQ: 2020 Ceiling Fan and Dimmer light wall mount control compatible with SmartThings and Alexa?
As far as a humidity sensor, all of the ones that I know are surface mount on a wall, they wouldn’t be able to detect humidity very well if they were inside the wall. So they would look a lot like a thermostat. Would that be acceptable? Or were you in fact trying to measure humidity inside a wall?