> this doesn't need to assign consciousness to simpler computations (rocks, buildings, simple cells).

That necessarily follows, I think. The quantum processes in a rock are also a form of computation and, therefore, inhabited by some rudimentary form of experience we might call, dunno, "rockness". I don't see an easy way around it. Perhaps at absolute zero all experience stops?

I have no answers, but your questions are precisely why I find this fascinating to think about!