Maybe getting LG Gram laptop will surely at least make sure that panel is from LG. From notebook check it seams like their panels are of higher quality than the rest of Chinese factories. Regarding certification, I have come to conclusion its obsolete. Generally certification does not work, there needs to be actual QA stamp with flicker free test results in the similar fashion as colour grading is done. This will make sure every single unit is tested, rather then product line itself with one or two units actually tested.
Note however, problem probably is not PWM anymore. I picked up my old PWM laptop and it is easier on the eyes than modern laptops. The problem is - there is a big stack of various signal modulation techniques including temporal dithering, and to be honest there is such a mess that nobody knows anymore what is causing these problems. Need to undo the onion slice by slice in order to get to the bottom of it. Or at least find GPU that is transparent in providing full control of firmware controls to the user. Intel, AMD, apple silicon, they all copy from each other, generally the same boat full of crapware.