What is odd about that AppArmor rule is that (from what I can see) /sys/dev/char is full of symlinks - but AppArmor mediates the real path that a symlink points to - so perhaps it may be enough just to be able to list the contents of /sys/dev/char to get this working - ie an AppArmor rule like:
/sys/dev/char/ r,
If so, I think it would be appropriate to add this to the wayland interface if it is now required by libinput.