I tried the Elekworld EBS screen today. My Opple Light Master Pro light meter says it was "low risk" at all brightness levels.
At >50%, it returned a flicker index of 0.0116, 5.34% modulation depth, and Opple measured 30,118Hz PWM frequency, but the accuracy of that is unknown once the frequency gets that high. At 10% brightness, it still said it was "no risk" (which is ideal), but flicker index went to .0723, 29% modulation depth, and the PWM frequency said 30,000Hz. Long story short, I do not believe PWM is actually in use on this EBS Incell screen. If it is, it is very high frequency and should be OK for PWM sensitive consumers.
Why didn't I ultimately keep iPhone 15 with the EBS Incell display? The tradeoffs were a little much for me. The color accuracy was a little bit off (on par with Android phones), the slightly raised display, and most importantly the heat generation and power consumption.
I do think this would be a viable option in the future when iPhone SE3 and iPhone 11 are no longer supported. So that's good. But there are tradeoffs. I would NOT recommend the NCC Prime display because that very likely used PWM at 480Hz.
Here's hoping major improvements with iPhone 16.