"but it provides the standard EFI booting interface so it's at least somewhat true." AFAIK, it just provides the uboot-uefi interfaces, which are only standard

"but it provides the standard EFI booting interface so it's at least somewhat true." AFAIK, it just provides the uboot-uefi interfaces, which are only standard if you are okay with throwing out the vast majority of things marked mandatory in the UEFI specification. The efi bits are just a tiny shim over uboot that provides just enough of the UEFI protocol interface to boot grub/etc from some subset of the available devices. Its a vast improvement over uboot by itself, but just barely scrapes the surface of fixing the arm boot problem. On many of the platforms there still isn't a uboot/pcie driver so booting from NVMe rarely works. None of uboot-uefi supported platforms provide the full set of UEFI drivers/protococls required by the spec, so its a crapshot if one deviates much from the expected emmc/sd boot path whether it works. In a few years that might change because there continues to be a fair amount of ongoing work to make it more spec compliant but as of today, its a bit of a misnomer to call it uefi. Going forward some of this work is going to be quite difficult as the core architecture of uboot still isn't even segmented sufficiently to support UEFI runtime services, or ACPI platforms.