UEFI is a weird environment. I'm not sure you can take an off the shelf OS and turn it into a UEFI application, because of things that are missing or restricted versus running standalone. But once you exit UEFI bootservices, you lose most of what UEFI provides, like storage access.

Easier would probably be running something like a single guest hypervisor that would essentially translate the storage (and NICs) into an interface the OS understood.