I think a good empirical observation that supports such an independent reality is that I have first person access only to my states and not of yours, or other people in the world. I still remain hungry when you eat food, remain thirsty when you drink water. I do not feel the pain of you burning your finger etc. The argument extends to the animate and inanimate world as well. I should be able to directly access the conscious states of my cat if the same I was everywhere. Evidence that some yogi can do that (direct first person access to other people's subjective experience) would be a defeater for the diversity of entities hypothesis. Till then observations show that the my first person experience is disconnected from your first person experience and is sufficient to ground the diversity of entities hypothesis.That was interesting reading indeed. I'll admit that I haven't been following it.
My perception is that materialism is essentially predicated upon the independent reality of the observed from the observer. If one takes that as an assumption, then certainly the philosophy of Vaisheshika, and what you discuss in those posts, are solid. As such, regardless of whether one is a materialist it has value from an immediate perspective. However, to stand solidly as a philosophy materialism would need to prove, rather than assume, that pre-requisite, and I don't see any way that can be done given the fact that external verification is impossible.
Note that it has become possible to observationally demonstrate when two (or more) 1st person consciousness-es have become unified. For, science has done it with its "gizmos" already.
Interconnected rats' brains create organic computer
Note that QM and Relativity shows that matter-energy-space-time is one interconnected network and its elements cannot be truly isolated from each other. But this remain within the purview of a physicalist Vaisesika ontology.