I jpst googled it and got these steps (haven't tried them yet):

To set up a Nix service in your Guix configuration, you need to enable the service in your configuration file, typically located at /etc/config.scm. You can refer to the Guix documentation for detailed instructions on how to properly configure and manage services.

Step one: Open config file

Step 2: Enable nix service

(use-modules (gnu))

(operating-system
  ...
  (services
   (cons* (service
            (nix-service)
            (nix-configuration
             (nix-channel "https://nixos.org/channels/nixos-23.11"))
            )
          ...)))

Save the file and reconfigure:

sudo guix system reconfigure /etc/config.scm

After reconfiguration, verify that the Nix service is running correctly by checking the service status:

systemctl status nix-daemon

Additional Notes:

• Ensure you are using the latest stable version of Guix to avoid compatibility issues.

• If you encounter any problems, consult the Guix documentation for troubleshooting tips.

• The Nix service allows you to use Nix packages alongside Guix, providing flexibility in package management.

Hope this helps!