Why do you think that there's something that it's like to be a rock? Assuming panpsychism, you still need to come up with a reason that consciousness is aggregating at the "rock" level, rather than at the mineral crystal level or what not.
Is there something it is like to be a severed limb? What about a clipped toenail? A pile of leaves? It is not obvious that just because we as humans identify something as “an object” that it must follow that that object has an internal experience.
There is so little to hold on to, given that the rock has no brain, no senses. To me, that implies that there are no concepts, there is no abstraction. Given that most of the universe is gas and rocks, and not brain, it makes me wonder a bit.
My approach is not scientific in a direct way, but I think that, in the long run, it might be helpful to come up with new ideas about reality.