But can it say “I don’t know” if ya know, it doesn’t
It's just statistical text generation. There is *no actual knowledge*.
It's just generating the next token for what's within the context window. There are various options with various probabilities. If none of the probabilities are above a threshold, say "I don't know", because there's nothing in the training data that tells you what to say there.
Is that good enough? "I don't know." I suspect the answer is, "No, but it's closer than what we're doing now."