You can not be convinced Turing complete is relevant all you want - we don't know of any more expansive category of computable functions, and so given that an LLM in the setup described is Turing complete no matter that they aren't typically deployed that way is irrelevant.
They trivially can be, and that is enough to make the shallow dismissal of pointing out they're "just" predicting the next token meaningless.
Also people definitely talk about them as "thinking" in contexts where they haven't put a harness capable of this around them. And in the common contexts where people do put harness theoretically capable of this around the LLM (e.g. giving the LLM access to bash), the LLM basically never uses that theoretical capability as the extra memory it would need to actually emulate a turing machine.
And meanwhile I can use external memory myself in a similar way (e.g. writing things down), but I think I'm perfectly capable of thinking without doing so.
So I persist in my stance that turing complete is not the relevant property, and isn't really there.
But it is trivially possible to give systems-including-LLMs external storage that is accessible on demand.