I got it!
I had to step through the final steps in this area to get it to work, but it now boots!
https://en.opensuse.org/SDB:Encrypted_root_file_system
I guess that means I need to actually set it to require me to sign in manually instead of auto-sign in, huh?
(I had it as auto-user login because it wouldn't do anything without the password before, but if it's doing that automatically, I'll need the OS to make sure the user is doing the right user things.)