I should rephrase on the first one. We only have one source of reference for what thinking is and where it happens.

On the second one, yes there can be multiple ways that consciousness can manifest in wildly different systems, but what theory do we have that would validate these other different kinds of consciousness? Without that theory for validation the safer bet is to stick with what we already have a reference to, unless the claim is that consciousness is such an easy algorithm it can easily be stumbled upon by all kinds of systems, i.e. a bunch of matrix multiplications that doesn't even run in real-time (it executes prompts and then stops). I think that is not likely in my opinion.