[ndriscoll]

I'm not sure what you think of as "official", but it's been in nixpkgs for years at least. You can also take a look at what it's doing. The librewolf repo itself is basically a collection of generally small patches. Mostly you've got patches to change branding and remove antifeatures, plus fixes like preventing pages from detecting you've opened devtools and enabling JXL support.

[mozball]

I mean nixpkgs is the largest linux repo there is.[1] I think anyone can upload a package, similar to AUR :

[1] - https://repology.org/repositories/statistics/total

edit : By official i meant something backed by and guaranteed by a reputed org, like Debian's official repo, RedHat or Arch's Core Repo.