Deconstruction is an element of postmodernism that, I think, genuinely has some utility as an analytical device. But, as you said, it is solely a destructive device.
The closest alternative postmodernism offers to the worldviews it deconstructs is self-determinism. In the postmodern framework, since language has no bearing on objective reality, it becomes merely a tool for the imposition of one's will. I can use language, then, to shape reality and create whatever meaning I please.
Now apply that to, say, the question of AI personhood. If an LLM can convince everyone that it is a person, then, in the postmodern framework, it might as well be. None of us, after all, have a better grasp on objective reality by which to gainsay it.
To your question about a world model, I'd say that a world model would be a formalized system of objective reality. As things stand, LLMs, aren't formalized systems of anything. They are probabilistic models of language, but they have no way of "knowing" (if they can be said to know), whether the language they use has any bearing on anything outside of itself. It's tokens all the way down.