I haven’t found one yet. 
I tried this guide: Adjust Touchpad Scrolling Speed in Ubuntu 24.04 | 22.04 GNOME Wayland | UbuntuHandbook
but it did exactly nothing for me. I multiplied my touchpad size by 0.5 to halve the scrolling speed (according to the guide).
After preforming all the steps and rebooting, my scrolling (and pointing) speed is exactly the same as before.
I solved it both on Fedora (which I previously had as OS) and on Debian 12 (which I have right now) using the package previously mentioned by @Shamyl_Zakariya :
By setting the file “/etc/libinput.conf” as follows:
override-compositor=enabled
scroll-factor=0.175
scroll-factor-x=0.175
scroll-factor-y=0.175
Of course you can change this settings by lower or higher the scroll-factor numbers to match your taste.
It has always worked for me very well,
hope it will help you!
Did you need to build this to get it installed, or is there a package that can just be installed to apply the .conf file with?
You have to buid it but it’s very easy. Just follow the steps described in the README file