Nt has a dynamic HAL layer to adapt it to platforms. I'm not sure if it was publicly documented, but in any case yes the source code leak don't harm that kind of port, even if you "just" have to write a HAL.
The current PE exe format supports it. As well as a few Alpha, a few ARM formats, a few MIPS format, Itanium and of course x86. The big part would be finding a compiler that spits out the right code. The preceding NE format also did a few variations.