Second the suggestion of a Shelly 2. This will give you separate power controls for the fan and smart light. Set it up so the smart light relay is always on, and set up the physical switch as a “detached switch” that doesn’t operate the delay but just communicates an on/off state to your automation hub. You could, but don’t need to, get a second physical switch for your fan. Home assistant to create automations with whatever humidity sensor you want to use. This is the setup I did in my bathroom, and I appreciated it when the smart bulb died because then I just threw in a normal bulb and re-enabled the normal switch function, but still had on/off smart control of the light.
“Hey google, remind me every night at 9pm to move that god damn elf on the shelf”
Kids, later: “Dad, why does that google screen in the kitchen say ‘move that god damn elf on the shelf’?”