I don't understand your point here. A (logical) relation is, by definition, a more general way of describing relations than a function, and it is telling that we still suck at using and developing truly relational models that are not univalent (i.e. functions). Only a few old logicians really took the calculus of relations proper seriously (Pierce, for one). We use functions precisely because they are less general, they are rigid, and simpler to work with. I do not think anyone is working under the impression that a function is a high fidelity means to model the world as it is experienced and actually exists. It is necessarily reductionistic (and abstract). Any truth we achieve through functional models is necessarily a general, abstracted, truth, which in many ways proves to be extremely useful but in others (e.g. when an essential piece of information in the particular is not accounted for in the general reductive model) can be disastrous.
I'm not a big fan of philosophy. The epistemology you are talking about is another abstraction on top of the physical world. But the evolution of the physical world as far as we know can be described as a function of time (at least, in a weak gravitational field when energies involved are well below the grand unification energy level, that is for the objects like brains).
The brain is a physical system, so whatever it does (including philosophy) can be replicated by modelling (a (vastly) simplified version of) underlying physics.
Anyway, I am not especially interested in discussing possible impossibility of an LLM-based AGI. It might be resolved empirically soon enough.
