Kray
I suffer greatly from PWM. I can only use the phone when selecting a brightness outside of the PWM range. The display uses PWM at lower brightness settings, and when you increase the brightness in steps (there are 255 steps) there's suddenly a point where the PWM abruptly stops (at 68). Unlike for example most Samsung AMOLED display which flicker at even full brightness (255).
I also discovered that flicker seems to not trigger me when the difference in amplitudes is very small. Like the leftover 60 Hz flicker AMOLEDs generally seem to have when PWM brightness control is disabled. The OP3 has it, and the guy who created the "no PWM" kernel for the Galaxy S7 wrote about it, too. OLED TVs seem to have the 60 Hz flicker, too, but usually their flicker spike is much larger than on AMOLED phones. It can be seen in notebookcheck.com and rtings.com reviews, and also with digital cameras and the flicker tester app. On most devices low brightness PWM flicker is basically just on/off, which is the highest possible difference. I'm even triggered by 100 Hz of some smaller incandescent bulbs. I tested the bulbs with Viso System's flicker tester smartphone app, which showed me that they had a noticably larger flicker index (difference between amplitudes) than standard sized bulbs. Everyone probably has different flicker thresholds. I remember the AMOLED 60 Hz leftover flicker has a much lower flicker index than standard incandescent bulbs (yet those light sources are not directly comparable - one is wavy, the other is rectangular). What I want to say is that the leftover flicker might be that small that it might not be triggering anyone, not even people like me who on top of all this are affected by certain home or office non-LED lightings.