With commit a4df575, we can get a minimal gnome-shell on GuixSD.
Make sure you have elogind and upower-daemon services running,
and add the following packages:
adwaita-icon-theme, gnome-session, gnome-shell,
gnome-control-center, gnome-settings-daemon, dbus
to the packages field (to use with the silm login manager) or
user profile (then add 'exec gnome-session' to ~/.xsession).
Please give suggestions :-)