Guix actually makes an effort to make extensions of the maintained Guix channel as easy as the design choices allow. You can extend Guix in various ways: adding whatever channels you find or maintain yourself, extending it by setting GUIX_PACKAGE_PATH to a bunch of files, or by telling Guile to load some modules from somewhere else with "-L /where/your/files/are".

Guix doesn't care what software you install with it. It doesn't demand that you subscribe to any philosophy. The project just chooses to only package and distribute free software in the main channel. There are projects that have dedicated themselves to extending Guix with non-free or ... weird software. Guix will never go out of its way to make using those channels harder.

But if you dare to use the non-free channel, you get shouted at if you try to ask for any form of assistance, even for problems entirely unrelated to it. Speaking from experience.

wat? I'm using channels providing nonfree software. Even "worse", I contribute to those channels.

These channels are not for #guix, because the discussion there is meant for the base channel provided and maintained by the Guix project; but on #nonguix, or #guix-hpc (for e.g. guix-science, guix-science-nonfree, etc) you get to discuss these channels all you want and get help.

Using nonfree packages in Nix feels like buying wine at the grocery store: small, infrequent, ephemeral hassles. Using nonfree packages in Guix feels like having to go to a small, obscure package store across town.