"Being" surely does not have more complexity than particle physics. Particles are already beings.

I don't think mind designs are dependent on their underlying physics. The physics is a substrate, and as long as it provides general computation, intelligence would be achievable in a configuration of that physics. The specifics of those designs may depend on how those worlds function, like how jellyfish-like minds may be different from bird-like minds, but not the common elements of induction, analysis of inputs, and selection of outputs. That would mean the simplest a priori mind would have to be computed by the simplest provision of general computation, however. An infinitely divine Turing Machine, if you will.

That doesn't mean a mind is more basic than physics, though. That's an entirely separate issue. I haven't ever seen a coherent model of God in the first place, so I couldn't begin to judge the complexity of its unproposed existence. If God is a mind, then what substrate does it rest on?

We don't know that beings require particle physics - if the only animal I've ever seen is a dog, that is not proof that zebras don't exist.

I'm not saying that there isn't complexity in the word "being", just that I'm not convinced that your argument in favour of there being more complexity than particle physics is good.