Regarding, the S8. I was about to give up hope on it. Until I read another member talking about cf.lumen. i installed that on a whim and it helps a TON. I am not rooted though. Using that in combination with another filter app makes the phone usable at night when I love to just drench myself in the internet, Amazon, and just where ever I wonder on the internet. So far cf.lumen with the s.filter. it's like a deep breath thankfully.
Its not perfect though. But its like my S5 which I never had strain with except a much better picture.
Also, I scraped the leds on my motherboard to not allow them to work and my video card. This helped so much. But then my video card and mb stopped working. So pls don't do this to your system. Quick way to loose money.
Also, I haved noticed fans are not good, mirrors are not good and have only one source of light in the room is best for me. I'm torn btwn fluorescent and leds but leaning towards led. This also includes sun. Sunlight must be blocked for a good viewing experience in my case. And I mean all of it.
Anyway, hope this allows ideas to exist and maybe allows oled screens to be more friendly as that is where it seems like most smart phone manufacturers are going.