[zinekeller]

> Is there a way Intel can expose microcode and commands to outside so compilers can directly target them instead of X86 instruction set?

Maybe, but MOV is still MOV, so Intel, for the most part, is simply using a subset of x86 (or AMD64) instructions. Except for a few proprietary commands used to implement the more complex commands, most simple instructions are implemented as-is and are passthroughed anyways.

> If yes, would there be anything to gain or lose?

Gains: Very slight faster performance (reduced lookup is always great, but realistically it doesn't matter unless you're doing supercomputer stuff).

Losses: It's pretty much like the kernel land of Linux or NT's undocumented functions: subject to change, fully not supported. Also, cannot be done on the current CPU families anyway since that the microcode can't be updated in such a way that it is worth it.