[nextaccountic]

> I found this: https://guix.gnu.org/en/packages/ which is a meager list without any link to the packaging source.

I clicked the first

https://guix.gnu.org/en/packages/python-pyxel-1.4.3/

It says "Package source: game-development.scm" linking to https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages...

It's a lisp code that does what a shell script might do, but declaratively. Indeed it isn't much different from an Arch Linux PKGBUILD.