@exalted So you would need to enroll when the MokManager Utility shows up on boot then, use the root password when it asks.
Did you see the nvidia drivers install via rpms, else if you look at the output from zypper lr -d you should see an nvidia repo present? Also maybe post the output from zypper se -si nvidia
For GSP firmware see https://forums.opensuse.org/t/todays-update-4-19-broke-graphical-interface/174354/18