You gotta do the measurements. It's probably not even that hard, all you need is a USB mouse emulator (any microcontroller with USB peripheral support can do this and there are tons of examples) and a photodiode.
will absolutely do this, the microcontroller and mouse emulation part is solved for me already so I just need to get an appropriate photodiode and... profit
The problem with this is more so that I would still have to record this "IRL", as recording it in software is just... meh (I mean, I could try), and I just don't have the equipment for that (I demonstrated as much there), so I will probably end up doing the Pico + light sensor thing as described there. Should be more reliable anyway (something very similar has been done already, and successfully), so... yeah, that.
will try again with a photodiode instead, since it's known to be a valid way to measure stuff like this, and it seems precise enough at that
if it isn't this, then I'll probably have to dig into
libinputor something