Sonoma 14.4.1 - just updated and now it dies on during load

Mid 2014 iMac, was perfectly running Sonoma 14.4. I always keep OpenCore up to date.

The update process was nothing spectacular; after the MacOS update, I patched the system, which re-booted as normal. I selected the OS to boot into, entered my password, and items started to load, and then it died as it brought more color into the photos widget.

Do you have any ideas? I can start with single-user and verbose, but I don't know how to diagnose a Mac.

Recovery won't let me use a backup; it insists I use Migration Assistant. I can boot into Monterey, so the machine isn't dead.

Author: @Informal-Market6871