I do not think I will work on this in the nearest future, but so that it does not get lost and anybody interested could take it. For compatibility with very old Windows installations and maybe Windows 7 we could add some basic support for legacy hardware booting.

An interface of the tool could take an optional(?) device path of the MBR volume and boot it. For most computers and DuetPkg we will want to utilise EFI_LEGACY_BIOS_PROTOCOL. Some older macs need more hacks, but I do not think they need to be supported[1].

[1] https://github.com/agners/rEFInd/blob/1af2fbe86e90185a0b62064e4c2dd7b801f17523/refind/main.c