That's beyond me and you're probably at least partially right about kernel architecture coming in to play.

You might find this interesting: https://en.wikipedia.org/wiki/ReactOS

For non-driver stuff if you were going to ask, "what if we just put a layer between the application and kernel and convert all the calls?" That's basically what WINE is.

Edit: This is a bit closer to what you were asking for, but I'd never heard of it before. https://en.wikipedia.org/wiki/Longene

tl;dr: It's been tried but either died off or isn't fully functional after decades.