[cmurf]

The pre-boot environment needs to find the kernel and initramfs somehow. My guess for how Apple is booting from APFS, now that it's all APFS, without a separate recovery partition? They've got this minimalist EFI jumpstart code in the firmware, it loads the EFI file system driver for APFS, and now it can locate the bootloader, kernel, and kext cache.

For a long time Apple has had an HFS+ driver baked into the firmware. The way APFS is implemented with EFI jumpstart, they've got much less filesystem code in firmware.