Maintaining a firefox fork is a much bigger job than putting `--with-unsigned-addon-scopes=app --allow-addon-sideload` in the package build script.
Distros already share effort implicitly because maintainers of distro X often look at what distro Y is doing for that package. Also users compare distros frequently and will tell the maintainer of distro X that the same thing works with distro Y.
Distros already share effort implicitly because maintainers of distro X often look at what distro Y is doing for that package. Also users compare distros frequently and will tell the maintainer of distro X that the same thing works with distro Y.