If these conscious experiences of particles are entirely encapsulated within them, and not manifested in their external behaviour, then I don't see how any form of aggregate consciousnesses could form. If the atoms of my body are conscious, what does that have to do with the consciousness of my brain? It can only be relevant if those consciousnesses interact or merge or coalesce in some way, and how can they do that without interacting beyond the interactions described by physics?

Clearly my consciousness has physical consequences. I am an active agent and act consciously. Therefore if my consciousness is composed of these, then the consciousness of those particles must have physical, measurable consequences that should be testable.

The fact that this line of reasoning is entirely absent from any of these philosophical ruminations is I think telling.