The Lenovo Chromebook Duet uses ARM, not x86, so I don't think MrChromebox supports it. I'm unclear on whether ARM Chromebooks even can support coreboot and/or edk2; do you happen to know if that's possible?
arm chromebooks usually run coreboot too; the utility of edk2 there would be questionable, as on none of them ACPI tables can cover all the HW, so u-boot would be good enough.