Can an 32-bit OS run on multiple 64-bit CPU cores?

[Abaddon_ire]

Yes. Computer and software companies have patents and copyrights on their products and have licencing agreements with each other, so not all software or hardware are interchangable. Just like a restaurant won't let you bring food in from another joint and eat it out in the open. 

I am not saying it is impossible to make the changes you want, but if you can't then one reason may be because of what I said above.

My question was why does 32-bit Windows 10, if run on Intel Core i5 8th Generation, appear to run only on 1 core. If the processor was somehow modified to accept only certain OS-es, what I'd reasonably expect would be that it rejects free Linux, rather than proprietary Windows 10.

https://docs.microsoft.com/en-us/windows...sor-groups

So Win32 can't do it.