Thanks @stephane!
I removed cuda and get this:
:: linux54-nvidia-450xx and nvidia-450xx-dkms are in conflict (nvidia). Remove nvidia-450xx-dkms? [y/N]
I went ahead and said yes to it and now it’s updating. Going to reboot and report back, if need be.
FWIW, I found my other thread, which was similar (but possibly irrelevant.)