+1, this is important and I’d like to provide some info on a deep dive I did + links regarding why this hasn’t been implemented yet.
This issue was submitted to libinput requesting scroll speed configuration, and it was noted by one of the maintainers that this was not the place to request it, and rather it should be in the compositor or toolkits, mainly due to complex responses like kinetic scrolling being content-aware responses, which libinput can’t do since it doesn’t know the context the input is being used in.
This GTK issue requesting a flag be made in GTK for adjusting scroll speed, and a response from one of its maintainers Emanuelle Bassi, who says this is something libinput needs to do, tl;dr not a toolkit issue.
Basically, everyone disagrees on where this kind of thing should be implemented. My $0.02 is that libinput is too low-level for it to be implemented there, and this comment by the maintainer Support setting scroll speed (#185) · Issues · libinput / libinput · GitLab explains why in a clear manner. The question of whether it will be implemented in GNOME is two-fold:
a) Whether someone will come and implement the feature
b) Whether GNOME will even accept the feature in the first place (GNOME can be resistant to change if they believe strongly that it is not their place to implement the change, rather another project’s responsibility)
EDIT: Relevant MR as this is one implementation of scroll speed settings circa 1 year ago:
gtk!4672 (I can’t provide the link as I am a new user and the forum limits me to 2 links per post)