That sounds rather similar to superdeterminism.

Not really, superdeterminism postulates that the measurement outcomes are guaranteed.

Here, you could imagine the universe as being operated on by some giant Hamiltonian operator with a basis of eigenstates, and then the amplitudes will just deterministically evolve according to the Schrödinger equation. But the amplitudes only reveal information about probabilities of measurement, not measurement outcomes themselves.

[How such a measurement could occur (coming from outside this universe system) isn't physically clear to me but isn't relevant either.]

How is this not begging the question? "The universe is the universe" is not a satisying answer to, well, any question really.

It is not expressing a tautology, it is saying the universe is a single quantum field. Basically, a single coordinate in some Hilbert space.

And the consequences of that are what precisely? For that matter, what would the consequences be if it wasn't true?

>It is not expressing a tautology, it is saying the universe is a single quantum field

Probably should have said that, then.

Well... it did. I couldn't distinguish quantum monism from Everettianism with my lay-person's understanding of the physics. I've gobbled up Sean Carroll's Biggest Ideas in the Universe video series on YouTube, and read his popular books on the matter, but that's the extent of my knowledge.

X = X doesn’t seem to be either, but it took some thousands of years for us to grasp the ramifications of such a statement