The recently-developed glass coatings do an amazing job of reducing IR heat gain in car interiors.
We took delivery of our Model S Plaid with its full glass roof in August in southwest Florida. While waiting for delivery, I kept looking at the Tesla Store website for a pop-in mesh sunscreen for the new model, as the older Model S's with glass tops presented a real issue with heat gain. To my surprise, the full glass roof in the new Model S presented no problem at all. Even in bright sunshine, the glass did not become warm to the touch on the inside, whereas the earlier roofs became uncomfortably hot to the touch. I don't even check any more to see if Tesla is now offering the mesh screen, as I would not bother with it.
Although we received our Air at the end of December, south Florida still gets strong winter sunshine. We are having the same experience with the Air's glass canopy: it poses no problems with glare or heat gain at all. It took me a couple of weeks of driving in bright sunshine finally to quit putting my hand on the glass compulsively to be sure I had not been imagining how cool it remained.
Lucid has very effective IR and UV shielding in all its glass. I have used 3M Crystalline on other cars, including our earlier Tesla. I'm not going to use any film in either the Plaid or the Air.