Replace everything with non-smart devices before listing the home and this will be a non-issue.

If I bought a home with smart doorbells and cameras and other stuff, I'd rip it out and replace it anyway. Who knows if the previous owner still has them on their account, or can access them in some way?

It has long been common wisdom that you should rekey or replace the locks when you buy a home. The same logic applies to smart devices.