What would be the use-case for this? Most open source software is trivially portable across architectures. For the stuff that isn't there are code transformation tools like qemu-user-static.
Sure, one could use every computer program in existence without becoming a computer programmer and gain useful function from them, and this would not be wrong in any way -- but there are also those of us who wish to understand things at a very deep level...
There are those of us who not only want to understand how computer programs work -- but how ISA's work, how the underlying hardware works, everything down to the substructures, the the adders, the logic gates, the flip-flops, the transistors, everything...
And that list includes (but is not limited to!)... x86 microcode...
Or more specifically, microcode in general...