Low-level access to STM32 peripherals using JavaScript

but not really useful

Well, I was referring to accessing the value of the counter that's just counting up at a fixed rate - obviously it's useful when it's counting an external input - but that's what the COUNTING EDGES bit is for :)

Touch - Would that qualify for a component to build a Theremin-like instrument?

Yes, almost certainly. With a bit of fiddling I'm sure you could get it a bit more sensitive and could use it to control pitch/volume or something...