One of the challenges of using a large-screen device in the sun is that most screen technologies (including transmissive LCD and OLED, but excluding eInk and transflective LCDs) are inherently "black" -- they absorb light energy that hits them. Even when they're displaying a white screen, they're absorbing nearly all of the light hitting them, and then emitting their own energy.

One of my mild annoyances with the iPhone 12 is that there's no white option. I have a white iPhone 10, and it's essential equipment for me as a convertible driver -- on a sufficiently sunny day, the phone will overheat on the center console screen-up, even when it's powered off! But with the white side up, it's fine even on sunny days breaking 110 degF.

The only way around this I could see for laptops and tablets in the sun would be a return to transflective displays or other non-black options... which would also be a huge boost to battery life in well-lit conditions. But none of these techs seem to have comparable image quality, and there are some inherent challenges (potentially addressable, but challenges) with color balance etc.