I would rather have LLM directly generate machine code, and best of all, macro Assemblers are blazing fast for decades.
This is like saying that a strong man would rather dig a hole with his bare hands than use a shovel. Structured programming languages are force multipliers, it makes absolutely zero sense to forego them just so you can vibe assembly directly.
Use a working Go program as the prompt+oracle for cross-language port or direct generation.
You can't PGO that code, though. Also, I'm not sure it can generate architecture specific optimized (-march, -mtune) code as well.
Considering it just pulls and remixes blocks, this is a very tall order for today's LLMs, and maybe a couple of generations as well.
Calling GCC/clang at the back and emitting ASM is both cheating and has no advantages whatsoever as well.