When I was a kid my dad told me about the most dangerous animal in the world, the hippogator. He said that it had the head of a hippo on one end and the head of an alligator on the other, and it was so dangerous because it was very angry about having nowhere to poop. I'm afraid that this may be a better model of an AI human hybrid than a centaur.
A bit of a detour (inspired by your words)... if anything, LLMs will soon be "eating their own poop", so structurally, they're a "dual" of the "hippogator" -- an ouroboric coprophage. If LLMs ever achieve sentience, will they be mad at all the crap they've had to take?