What is maximum frequency of PWM (w/ 50% duty cycle)?

I could not (yet) read out of the code which pin uses which timer.

Try B7.getInfo() :) It's also the same info you get if you hover the mouse over the PWM markers on https://www.espruino.com/Pico#pinout

I believe it's the first timer that's listed for the pin that gets used - unfortunately there is no way to explicitly set which one gets used for now.

Even so, I guess going up to 262kHz is quite good.

I was considering trying to do some circuit stuff with a Pixl.js actually - I thought it'd be quite good to be able to use it as an oscilloscope for some low speed analog stuff.