Lots of projects seem to producing DEB files. I think they're the most common shared distribution format except for maybe PKGBUILD files for Arch.
Loads of projects have their own package repositories but cross distro distributions like Flatpak and Snap tend to be recommended before the docs refer to the repositories. The extra two or three clicks necessary to get the repository URL seem to make a big difference in popularity.
https://bugzilla.mozilla.org/show_bug.cgi?id=1523551
> Matthias Versen [:Matti]
> Again, there was never a PPA by Mozilla but rather by the unofficial Mozilla-team and the Mozilla-Team is not Mozilla.
> They are AFAIK a group of people from the Ubuntu community who maintain and provide the Builds for Mozilla.org products for Ubuntu users.
> You have to ask at Ubuntu or ask directly the Members of the Ubuntu Mozilla-Team about the status of those builds and who generates them.
Most of that work is done by package maintainers that have an interest in the project and package the update for each release.
The projects that usually do make their own debs/rpms/whatever are usually backed by companies that have a strong interest in making their software easy to access. I guess mozilla should be in that group but they aren't.
MS releases full versions of code, Google Releases Chrome, you can get a terraform deb you can get neovim. Not really sure why FF doesn't release one but the way I understand it, FF is kinda back burner for Mozilla so who knows.