Linux is just the kernel. GNU as a name for the system is okay, while Linux is arguably not. GNU/Linux is just a compromise for those who insist on naming Linux. Also, from the projects website, we have

"GuixSD is a distribution of the GNU operating system centered on the GNU Guix package manager. It uses the Linux-libre kernel, and support for the Hurd is being worked on."

https://www.gnu.org/software/guix/about/