Support on button scroll for tablets
Summary
It's common for users of graphics tablet devices to want to use the tablet as their primary pointing device at least some of the time. Although some dedicated graphics applications (GIMP/Inkscape etc) implement specific tablet support, most applications do not, and only respond to generic scroll events. It's therefore very common for tablet users to bind one of the stylus buttons to "on buttons scroll" so that stylus movement can be used to scroll/pan a page. AIUI libinput does not currently recognise on button scroll as an option for most (all?) tablets so there's no way to replicate this directly in libinput. On X11 there are ways around this but on Wayland you're stuck with whatever libinput exposes for your device.
Feature details
I apologise if I've misunderstood where the problem lies here. I've searched fairly extensively for how to achieve this on Wayland. From reading various bug tickets / StackExchange questions / Reddit threads it seemed like the only way that this could work is if libinput supported it natively, but I'd be very happy to be corrected if there is already some way to achieve this that just needs the desktop environment to expose the appropriate configuration options.
Affected Hardware
AFAICT, at least most simple tablets without other scrolling support - e.g. Wacom ONE.
Implementation in Other Systems
Under X11 it's possible to do various things like e.g.
/etc/X11/xorg.conf.d/00-mouse.conf
Section "InputClass"
Identifier "system-mouse"
MatchIsPointer "on"
Option "ScrollMethod" "button"
Option "ScrollButton" "3"
EndSection
or using xswetwacom
if libinput is not involved.