https://bugs.winehq.org/show_bug.cgi?id=46584
--- Comment #1 from C0rn3j spleefer90@gmail.com --- And since this bugtracker seems to crash on certain unicode characters, here's try #2 with the comments:
Tobias: For xorg its freedesktop itself, for wayland its the respective rendering engines, including wine upstream. You'd need to ping wine, mutter (gnome wayland), xorg, kdes painter, sway and more. All would need to agree on a per-mice standard that isnt xorg multiseat (which is a thing). https://wiki.archlinux.org/index.php/xorg_multiseat
Or just ask wine to add the option to modify udev rules and natively grab mouse events from /dev.