hansennnnn Based on my experience using both IPS and OLED yes I believe that PWM is not the issue for you, it is certainly not the main issue as of course there is no definite diagnosis for what we are all dealing with here.
I use the Twilight app default settings which mean it is only in use between sunset and sunrise. You can customise it so that it is in use all of the time but I doubt that will help with your symptoms.
From everything I have read on this and other forums about the issue and my own experience over the last 14 years it is clear that there is not one solution or way of managing the issue for everyone as we are all dealing with different levels of symptoms, whether it is eye patching, diet, supplements, using LCD screens or other methods the reality is we are all searching for that magic solution or just a reduction of symptoms at best.
My eyesight is good, I do wear contact lenses and have regular checkups. Back in 2014 my then optician said it is most likely a communication issue between my eyes and brain. More recently in 2023 my current optician said I may have "Pattern Glare" though I think this only relates to the issue I have with patterns on clothing.
My theory is that as my main symptom is tiredness with the eyes it is a similar when exercising or going to the gym and your muscles become tired. The more you train the stronger your muscles get and therefore the more you can do.
Replicate this theory with my eyes and so when I use a screen for the fist time and I get mild tiredness such as with my Pixel 3a and Motorola Edge 30 Neo I believe by using it over time the muscles in my eyes get stronger and eventually the tiredness reduces.
I think that Motorola mobile phones appear to be the best screens to use for many people based on feedback on forums.