I stumbled on an interesting device from ThirdReality. Rather than totally replacing a normal light / fan switch with a Zigbee / ZWave / Wifi switch, this one snaps on top of a regular toggle or rocker switch. This means that there is no need to deal with the electrical wire, the small gang box, or the potential issue associate with inductive motor load for bathroom fan (which might require having to reset the switch at the electrical panel and / or re-associate with the ZWave hub). Instead, you just screw this device on top, and it would physically trigger the button. I haven’t tried it myself. It does look a big uglier as it pops out, but for those hesitating the electrical work, this is a very good solution.
Smart Light Switch Gen3
or
https://3reality.com/product/zigbee-smart-switch-gen3/