They have some explicit examples of physics explainable by quantum gravity that resolve but are undecidable, n-body thermalization being one. Of course that’s given a sort of hand wavey understanding of quantum gravity, I guess one that they say should tell us whether a system thermalizes.

EDIT: I should also mention the idea that reality can tell us if a statement about a theory is true, given that the theory is an accurate description of reality. So if there’s an accurate Turing complete theory of reality, and we see some process that’s supposed to encode a decision on an undecidable statement being resolved (I guess in a non-probabilistic way as well), then we can conclude that reality is deciding undecidable statements in some nontrivial way.