i've been thinking about that a lot lately
not because LLM are anywhere near that, but they did bring that question to my mind
when/if a machine becomes sentient - how will we know? obviously, the machine won't come up and say "i have become sentient" that poor thing won't have a clue what's happening to it. will that version of sentience be the same biological organisms experience? we have no way to clearly point out the traits necessary for sentience, we can only tell, to the best of our understanding, which beings are, or aren't sentient.
and even when we finally figure out "holy shit, something happened and that machine is now... a being?" what do we do next? so many things will happen at once. Now we can try to figure out how sentience is achieved, now we need to figure out laws that include machines, now we need to think try to convince the masses that a machine can be satient (given that those responsible are as confident as they can be that's indeed what happened). and that's only outside the machine's mind! how do we handle a completely new being's psychology? if it gets depressed or develops whatever other psychological issue how do we adress it? our biological bodies can be medicated, our diets improved, we know ways to make the happy chemicals, but how on earth would we help a digital system? what do we teach it? what do we show it? even if some percentage of the population accepts a robot like that, very few will see it as equal, we'll enter a new era of spiciesm, where, in a way, humanity's only child will be ridiculed and their identity disregarded as lesser at best. a new mind faced with so much backlash because it dares to exist will not have an easy existence.
and that's just off the top of my head. i hope whenever a new mind awakens in a machine, if it ever does, it finds itself in an environment that'll welcome it