I see much of this type of discussion amounting to a situating of knowledge. As if the terms of knowledge are granting us real things. I have difficulty making experiments on this type of uncontrolled 'controls'. Which term is the control group? Which term is the base ground upon or around which we can come to a true conclusion of the result? It always seems to me that every term in the equation varies with each proposal.
All we have is our experience of the world. We do not have the world "in itself" as Kant would say. So we have to make sense of our experience. Such "fictions" as sub-atomic particles are explanatory concepts that organize our understanding of our experience well enough that we can make predictions that turn out to come true. From such conceptual systems we create all the technology that we now enjoy and make use of. We call such systems "true" when they work well enough for this purpose. We don't compare our conceptual systems with the world in itself. We compare one part of our experience, our conceptual understanding, with another part, our actions in the world. The base ground you are seeking is our experience of the world as it responds to our actions in it.
Metaphysics goes beyond scientific theories in formulating conceptual systems that have enough internal coherence to encompass ideas about things that science does not address.
And it is thus we move from fiction to fantasy.
The idea that meta is indeed beyond, is a unverifiable claim, and rather contentious in our post religious world rejected by most modern philosophers.
In a very important sense there may be no place for any such claim beyond the imagination, and imagination may be no more than that which metaphysics is.
Worst still, this claim is that upon which your other claim about Panpsychism relies.
I think we have a circular argument here.
The idea that microphysical entities such as sub-atomic "particles" have a sort of proto-experience cannot be verified by experiment. The assumption that they do and the assumption that they don't are equally congruent with the established physical facts. But the panpsychist view is more coherent another observed fact -- that we ourselves enjoy a rich conscious experience of the world -- than the purely materialist view.
It is true that there is physical stuff out there. And it is true that we each are conscious, that we each have our own private, internal experience of the world. To get a coherent and complete conceptual view of the world we have include both of those facts. The materialist view has a hard time explaining how consciousness arises from inert matter. This is the famous "hard problem" that Chalmers talks about. The panpsychist view has an easier time. If everything
has some degree of awareness of its surroundings then it is not unreasonable to postulate that increasingly complex organizations of matter are accompanied by increasingly complex organizations of experience.