Hello I've been suffering from PWM/Dithering issues for a couple of years now and sadly I see more people having troubles daily.
I know many of you can't use almost nothing from Apple but regarding macbooks I did not see mentioned so far the 2016 15 Pro whit the Intel HD 530 card. In 2016 when it got released I bought the 13 Pro straight away to see if I still get strained because the 2015 Pro was giving me insane eyestrain and headaches and voila the 16 13Pro had same issues.
So I thought what could it be then, so I went and bought the 12 Macbook too since it looked cool and I thought I'll be travelling more and use it like a tablet. But it did not strain me at all even after prolonged use(4h+) and that has Intel HD 515 graphics. So when I saw the 15 Pro has the same Intel HD graphics I bought it right away and I am writing from it right now feeling no strain at all after using it for more then 8 hours yesterday and already 2 hours today, been using it constantly since 2016 as my main portable PC.
It is not PWM free but has very high PWM frequency and still it's very easy on me. I've tried so many desktop screens, laptops both windows and mac and very rarely I can use something without some kind of strain. I've tried M1 Imac, M1 13 air, M2 13 air, 2017 15 Mac Pro, phones I won't even list them they're so many I ordered yesterday the Fairphone 4 since that's the only one people been saying it's comfortable and it's pretty recent so. Now im on the SE 3 but can't do whit the small screen anymore.
So I think for me atleast PWM is a smaller part of the problem, the biggest issue like I read on here before is the dithering and other software tricks specially Apple does to enhance the colors and the user experience overall.
I don't know what's whit the HD series in Apple but no matter what OS I used whit it and all updates since 2016 it bringed me no trouble at all. Sadly it does not support latest osx but it's still on Monterey and it gets updated regularly. I hope to find something usable since then.
Got a Lenovo Yoga Pro 7 coming tomorrow will let you know how it goes, bought a T14s a month ago and had to return it massive eyestrain after 30mins of use.