I have this one. But note that these things draw a lot of electricity.
they make heaters deemed 'bathroom heaters'
https://www.amazon.com/dp/B01NAQO4F1
but it's really just the plug that's different (like a hair dryer plug, a protective device)
Just buy a $25 heater, run it before showering, leave it on for a bit after you've left the bathroom, and leave the door open so the humidity can leave.