A Microsoft researcher built a goat-powered LLM in Age of Empires II to prove it's not sentient
(www.xda-developers.com)
There's fundamentally not much difference between our brain and a fly's, at the cellular level. We have fully simulated a fly's brain already. When given a virtual body, it promptly started acting like a fly.
I don't think LLMs are conscious or sentient. However, consciousness is likely just an internal illusion. There's no obvious reason we can't scale up from a fly to a human brain, other than difficulty. At that point you have a fully virtual brain that believes itself to be conscious, and can demonstrate sentience.