You could reduce any fact to an unknown with that type of troll reasoning.

Sorry that I came across as a troll. That was not my intent.

You can never know anything for a fact but you can get pretty damn close, and you absolutely can rule out anything that contradicts.

Lmao this statement itself is a contradiction. You first say how "you can never know anything for sure" in regards to descriptive statements about reality. Then, in the same statement, you make a statement relating to the laws of logic (which by the way are descriptive statements about reality) and say that you are absolutely sure of this statement.

Serious answer though - the scientific method is based on a couple of axioms. Assuming that these axioms are true, yes, you can be absolutely sure about the nature of things.

The idea that an LLM could gain consciousness contradicts the fact they lack memory and the ability to learn/grow.

You lack the understanding of how LLMs work. Please see how neural networks specifically work. They do learn and they do have memory. In fact, memory is the biggest reason why you can't run ChatGPT on your smartphone.

They're called machine learning but all the learning happens before they deploy.

Untrue. Please learn how machine learning works.