Much like how many of us use pip, gem, npm, composer, etc. on our Debian/Red Hat/etc. machines, you can also use Guix in the same way. For example, you are deploying a production web application and Guix had newer versions of some dependencies than your stable host system. You could use Guix to create a profile (a collection of installed packages, a bundle in Ruby terminology) that includes those dependencies for your web application to use.

It's possible to use pip and friends on a Guix system, too.

I personally do all of my Guix hacking on a Debian machine. They play very nicely together.