The heat rejection layer on the windshield of my Model X does a very good job where it's applied. It's only where the headliner would traditionally go, and I usually only notice radiant sun from the side windows since I'm not often driving into the setting/rising sun. It doesn't seem like the Model 3 has the same heat rejection, as I'm seeing lots of posts commenting about it being only privacy and asking for recommendations on heat rejection tint. For cost savings, I could see the Cybertruck going this route too, so you might want to start looking into heat rejection film.