I have never seen one. However there are very thin monitors available that you can cut into the visor yourself. Some are only 3/4" thick.
I finally have the backup camera that I want (I went through 3 of them to find one I like). My plan is to use the forward glasses holder for the monitor. Putting it in the visor would be a good idea if you do not have space to spare in the overhead consol (I do not have a sun roof). What I want to do is make the monitor fold down automatically with a small servo. It could happen . . .
Cheers