While the documentation does list quite a few useful details about the specs of the display, the PWM frequency is unfortunately not mentioned. A reliable measurement can only be done with a specialized device like an Opple Light Master. Here is some more research about the PWM flicker on the Steam Deck OLED: https://old.reddit.com/r/SteamDeck/comments/1882kys/analysis_of_the_pwmflickervisual_fatigue_of_the/

What is the PWM frequency with DeckSight? I’m pretty sensitive to that and my regular OLED model sadly strains my eyes within an hour. Maybe something like this could be a better alternative for me.

Oh, it does show up on desktop, not on mobile however.

Another GitHub project with no screenshots