Put UEFI on the chromebook!! Argh don't write it off, chromebooks are the best x86 platform by far. MrChromebox provides pre-made coreboot+edk2 builds for a ton of chromebooks, but you can make your own too.
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.
MrChromebox currently publishes only RW_LEGACY firmware (not full ROM, only replacing the stock SeaBIOS) for AMD Picasso/Dali and Intel Tiger Lake devices, but a) that's enough to boot whatever you want and b) you can build your own full ROM.
