The computer is physical, but the computation is (at least) a level of abstraction above the physical layer. The physical process may be the important part, not just the (apparent) algorithm that the physical process executes.
>but the computation is (at least) a level of abstraction above the physical layer
I think you're kinda right, but the tricky thing here is that the computation itself is physical too. The abstraction may just be whatever it is that the computation has in common with the thing it's modeling in brains, which could mean it, too, has consciousness, or is 'doing' consciousness in some sense.
If the physical process is "the important part" then that can be modeled in an abstract way, too.
We can run any algorithm using billiard balls:
https://en.wikipedia.org/wiki/Billiard-ball_computer
What I’m saying is that we don’t know that consciousness is just an algorithm. If the physical implementation matters, then modelling it might be useful or interesting, but it wouldn’t actually create the real thing. Maybe consciousness arises from a specific pattern of movement of electrons, but not from any pattern of billiard ball movements.
>What I’m saying is that we don’t know that consciousness is just an algorithm.
I caught that, I think(?). I would flag that the upshot or implication can be (1) something outside of physics altogether which I think, while romantic, is at the extreme end of extreme in terms of tenuous and inviting bad metaphysics, bad notions of emergentism etc, but there's also (2) something about the difference between how something is "embodied" which, as you note, still is about billiard ball style simulation at the end of the day, but can raise interesting questions about what kinds of simulations work.
I also do wonder of there's some kind of physicalist essentialism working its way in there. If there's something different about electrons that's importantly different, something about it (hopefully) is a physical property and as such able to be modeled. If consciousness is intrinsically and preferentially tied to a certain kind of matter, e.g. atoms, or brain-stuff, that starts to sound a little woo-ey.