[rekado]

No. While the core repository (we call that a "channel") only includes free software, there are no restrictions whatsoever on what you can or cannot install with Guix.

Guix makes it trivial to add third-party channels (such as nonguix, guix-science-nonfree, or other free software channels like guix-cran or guix-science) or extend Guix in an ad-hoc fashion.

You can also build an entirely private collection of packages if you want; from a file, from a git repository, from a Guile expression, etc.