Warning: this Guix configuration uses non-free software. Head to https://gitlab.com/nonguix/nonguix if you want to know more about nonguix.
Do not forget to set GUILE_LOAD_PATH:
export GUILE_LOAD_PATH="/etc/guix/core"
Reconfigure the system (this might take a LONG time depending on your situation):
sudo guix system reconfigure /etc/guix/config.scm