I did a brief search of Librem 5 with regards to PWM and came across this.
"But JTL, 200Hz is awful."
Well I agree, but what I'm trying to say is that it seems trivial to change in the kernel code.
That being said I still wouldn't buy a Librem 5 because it's a first generation product, and the Librem team seems to be overworked for such an ambitious project. I support of a private and secure smartphone, but implementing it properly is a different task entirely.