My non-expert and possibly wrong understanding: the difference is where the keys are stored. The LF solution keeps it all within the UEFI store, so you have to

My non-expert and possibly wrong understanding: the difference is where the keys are stored. The LF solution keeps it all within the UEFI store, so you have to put UEFI into "setup mode" so that their prebootloader can enroll keys, or you have to manually enter the key yourself within UEFI. In both cases, you need to deal with the UEFI user interface. The SuSE solution can also use its own key store, which means that the Shim itself can enroll its own keys in its own storage area using its own UI. The whole thing is really screaming for a flowchart, since explaining it all through text can be quite confusing.