2020 T350 HR ext 3.5EB
search a bit more on the forum. You can definitely upgrade this via aftermarket and I believe other have gotten the rear view camera to work on a larger screen. Search for Carbar, TiJoe installed a 10.1" radio...I can not see anywhere that states sync 3 on the window sticker. I will check with some local audio people. This tiny 4" screen is all but worthless. This is my first Ford product I have owned so I have zero knowledge of any of the Ford stuff. Had I known it was not something I could upgrade, I certainly would not have bought this van. The backup camera through this tiny little screen is like not having one at all in my opinion, and no rear glass (cargo) makes the camera pretty important.
I am assuming other OEMs deploy similar strategies with low level radio options.
Hopefully you'll find something that works for you.