I live in Clearwater, FL and deal with bright sunny conditions on an almost daily basis. The real issue is even with 2000 nits of brightness the iPhone 16 is not bright enough, even with anti-glare, anti-reflection, multi-coated and matte screen protectors. I’m finally able to see my screen by upgrading to an iPhone 17 PM with 3000 nits brightness.
The change in brightness isn’t really linear and the 50% increase is realistically perceived as only a 25% increase. But that’s enough for me to see my screen at high noon on Clearwater Beach (when brightness setting is maxed out).