chain load with EFI and file:/ URL

[NiKiZe]

The file:// was intended to load files from disk,
Everything that iPXE loads gets put in it's virtual memory fs, so when grub or anything else loads that is what it has access to and it does not know that it was loaded from disk and what the relative path is to any of the files that was sitting next to it.

So no the way you are trying to use it is not what it was designed for.

You could try to imgfetch all other relevant files so that it ends up in the same virtual fs, but not sure that will work eighter...

However there is one hack that works, using wimboot,
What you do is that you imgfetch all files that you need to have available,
The bootable file that you want to boot needs to be named bootx64.efi localy which can be don with imgfetch -n bootx64.efi file://grubx64.efi
and finally you chain to wimboot and that should create a virtual VFAT fs (which can be read by grub), and then boots bootx64.efi which is your grub.

imgfetch is the same thing as initrd and -n is the shorthand option for --name which you can find in the documentation.

PS might be wrong about the name bootx64.efi, but wimboot will tell you if that's the case