Surface Duo 2 Brightness

Hi all,

I hope this finds everyone well. This is probably a bit of a silly question, but I'm hoping to understand how screen brightness and brightness ratings work.

I was just reading an article about the Nothing Phone misleading customers by having a brightness of 700 nits (below that adverized). I use my Surface Duo 2 on 1/3 brightness (less at night), as anything more hurts my eyes and gives me migraines (so I'm not complaining about brightness). I was curious as to how the Surface Duo 2 rates, and Google informed me that it was 672 nits. Apparently other phones (like Samsung and Apple) are between 800-1,000 nits, which blows my mind.

My questions are:

1. Are nits the only indicator / factor for determining brightness? 2. If yes, wouldn't using brightness at those levels cause damage to the eyes? (Maybe I'm a bit sensitive, but I don't get how people could tolerate that). 3. I'm guessing the iPhone and Samsung have the same technology screen, but does different technology (e.g. AMOLED, OLED, and TFT) differ with brightness?

Thanks in advance.