+1 for some more information about code 660. It doesn't seem to be M1 related as I'm seeing the same issue on my late 2013 Intel-based MBP

Has anyone found the documentation for the new "Apps and Books for Organizations" server API? Cyrus just said to go to developer.apple.com but that's a pretty big site and I can't find documentation for the new API anywhere.

I'm interested to know the answer to this too, as well as what the purpose of the PrerequisiteBuild field is. Does that mean the OS needs to be on that build before it can be updated to the rapid security response in question?

Re-reading the "Integrating Declarative Management" document, and more specifically the section "Synchronize device state" I do believe that the endpoint is simply poorly named and the declarations are in fact specific to the device and not all the declarations the server supports. It would still be good to get some kind of clarification on this though.