Yes, and those will require MOK signatures as well, which is why DKMS wanted to enroll its key, once and for all; the password is only required once for physical presence approval, as demanded by the Secure Boot spec. That may explain your black screen at boot, actually. No Nvidia driver, because no MOK, no output; it’s SB at work. You’ll have to disable it first.
This is still the users helping users Discourse. Please contact Canonical’s professional support for anything beyond that. There may well be ways to do this in bulk, but you’ll probably not find the info on that here.
Plus, DKMS is required only for proprietary drivers requiring glue modules, which need to be compiled locally because of licensing limitations. Get rid of the dependence on those and no MOK enrollment is required. The Thinkpad, on which I’m writing this, is running without a MOK but Secure Boot enabled, so it can be done.