Having a model of the world (predominantly from vision, but also hearing and touch) surely does wonders for language acquisition as it provides the learner a backdrop against which to infer the meaning of speech. When an infant hears “look, a dog” and “look, a cat” in two separate instances, their eyes alone provide enough information to infer, at least at a high level, the meanings of “look, a”, “dog”, and “cat”.

It's pretty clear that humans, unlike LLMs, use external sensory data (the only external data we have, when you cut through it all) when they produce speech, as evidenced by the fact that they don't speak falsehoods that don't mesh with their internal data model. LLMs have such a weak model of reality -- it's whatever “sounds right” -- that they speak falsehoods all the time. The only way to give an LLM sensory data would be to encode every sensory experience people have into text.