Sorry, I misremembered, the native flicker frequency is at 200 Hz, I had to look up my notes again and verify by listening to my solar panel hooked up to a 3.5mm jack.

I forgot to mention, I actually managed to write a program that would dynamically rewrite the period and pulse width registers to play music off the screen backlight, based off a conversion of the Monkey Island tunes from https://www.thanassis.space/monkeyisland.html. It almost worked... except that whenever I decreased the period (raised the pitch), there was a random chance the new period would be greater than the current phase, and so the display would hang at full or zero brightness nonstop (producing a gap in the sound) until the 16-bit counter running at 0.98 MHz (= 125/128) rolled over, rather than instantly setting the counter to zero and turning the display back on. I've recorded my "best effort" attempt at music, at https://www.youtube.com/watch?v=7qt0ssFk410 (every recording has different gaps when pitch increases).