Well, looking at the mess that is most arm/arm64 SBCs, I understand why it’s nice to have a standard interface that can run (eg) grub. Can UEFI be much smaller? Also yes.

I think uboot is kinda doing that?

some arm64 sbcs support edk2/uefi btw. I make sure I just use those. Look for "Arm SystemReady" certification, which requires this