What do you define as "a computation"? If water runs down a hill following a windy path to the lowest point, is there any computation happening as it "chooses" its way? If you throw a ball up, is there any computation as it "decides" when to turn around and fall down? If a mirror reflects light rays, is it computing anything as it does so? When a fire burns, is there computation in its flames? When you drop string and it falls into a tangle, is it computing how to land? It seems to me that you could model some factors of those processes in a computer, but they are not in themselves computations.
Do you define computation so broadly as to be "anything matter and energy does"?
You can look at avatars (human faces on website chat bots) that try to add natural human-like movements, and their eyes move around in different directions governed by a random number generator; the result is that they don't look at all human, human eyes do move around a lot but not at random. Humans look at specific things in the environment, and that comes from having an awareness of the environment - people look at faces, windows, shadows, moving things, clocks, art, and not empty space, walls, nowhere, nothing. Even looking away "at nothing" and thinking has a distinctive look to it.
All of this is based on the idea that a human exists in a specific location, and the looking around is about getting information of what might be dangerous/advantageous to the human. I don't really see that you can abstract such a thing away from the meat body and do the same computation in an orbital computer with no inputs and outputs whatsoever, or on pencils and paper spread over thousands of square miles and thousands of years, and say it's the same thing. It's a bit like saying that a human can draw a stick figure or a horse, but a computer can use no ink and that counts as a drawing of everything, a universal drawing, without limits, gasp! Human style consciousness is part of our limits - our limited excent in time, space, amount of energy we can expend, mortality and risks of harm. Take all that away, you don't get a universal consciousness, you get a blank slate. Abstract of any matter and energy and specific situations, what is there to computer? And in a specific situation, a tired human sits like hot wood burns, it just happens. When you sit, is it computational sitting? When you open the irrigation valves on your field and the water flows down the grooves instead of over the surface, is that computation? When you trigger a stored memory release and the neuronal signals flow down the worn grooves of learned patterns, is that somehow different? If so, why, just because they're smaller or there's more of them? You can't grow plants with simulated water, why assume you can think simulated signal flow patterns?
> "What else could it be?"
A Buddhist monk walks up to a hot dog vendor and says "Make me one with everything". All our words and descriptions of things as discrete, seperate, entities with clear edges, are wrong (but useful). There is only one whole universe, no parts to it. You are what you eat, there's no place in your intestines where molecules change from being food and start being your body, it's a continuum. A sound is a pressure wave in the air, but you can't separate "the sound" from the moving speaker, the moving electric currents in the amplifier, the moving air molecules, the moving eardum, the moving ear canal innards, the moving electric currents in the brain, it's all one continuous system. It's not the case that "sound" is what the air does and those other bits are irrelevant, it's just convenient to talk and build things that way. There isn't really any sound at all, Vitamin D doesn't come from sunlight, the energy in sunlight affects vitamin D precursors in your skin. There is no separation between the light energy affecting your retinas and the consequent electric patterns in your visual cortex anymore than the sound is a separate thing.
In this model (wrong, but useful), there is no separate consciousness and no creatures which can be conscious. If there is any consciousness, it's the whole universe which has it in the sense "we are the universe experiencing itself", and your head is one (X,Y,Z,t) coordinate and the computer is another coordinate, and they are different by virtue of being different parts of the universe. Whether you can imbue the computer with the consciousness of a person stops being such an important question - you can clearly organise bits of the universe into responding like consciousness because you can have children and they wind new matter up into thinking, but that only says that "matter thinks", it doesn't say "matter /does/ thinking as a thing which can be separated from that matter". What else could it be? It could be nothing; some bits of matter exhibit complex behaviours and there's no more to it than that. Cameras aren't "seeing", why think eyes are "seeing"? Instead of discussing whether we can make cameras that see, why not discuss whether retinas interacting with photons are doing any more than cameras are, and seeing is an big fuzzy concept blob memory pattern and not a physical phenomenon that exists separate from matter?
You can talk about being "right handed", what does it mean to make a computation done in a computer with no hands "left handed" or "right handed"? It makes no sense to take that idea away from a creature with two hands in an environment where they use the hands to do things and have to deal with the limitations of having only two hands and no tentacles/tractor beams/prehensile tails/elephant noses/etc. Does it make any more sense to take "thinking" away from brains?