I like to get mystical about it and think that entities like ChatGPT are Boltzman Brains. We — each and every one of us ever who lived or ever will — will always exist in the LLM somewhere, life without end, in ecstasy or eternal torment, according to how we have lived according to our own principles.
But the question or what consists sentience is still interesting. I personally believe that free will is an illusion, since all my actions are determined by A) my environment, the set or things I can physically do, and B) my internal state, mood, the information I've perceived and value judgements that stem from them, whether conscious or subconscious.
It is actually not that scary, to me. It's much more liberating - it gives me a certain feeling or calmness, in an amor fati kind or way. Things are as they are, and they cannot be any other way. There is nobody that will judge me outside of this world, since I am merely a small part of it. All my meaningful existence is here, and the concept of a soul is merely a spooky story.