So I can only make it faster?

Is that sensible?

Don't use onValueChanged

use onMoved

then you don't need all of this other logic

We can make it slower with a number between 0 and 1.
I will need to implement a custom step that's all.
I am also hesitant of making the steps exponential, rather than linear.

I suspect that a scroll factor less than 1 may screw up discrete axis values. Not sure whether it might be a problem, though.

My testing went ok with a 0.1 scrollFactor, although not extensive (scroll in XWayland Firefox and in qtcreator Wayland mostly).

nitpick: I'd put the closing square bracket on the next line and you can drop the semicolumn

You can drop the semicolumn in there

ditto

Same comment applies than for mouse

ditto

ditto