It's difficult to say anything about experiential/first-person consciousness as we don't know what it is. Some say it doesn't exist and everybody is a p-zombie. That aside...

As you mention, there's a problem where if you want to know yourself fully - including observability of your mind - you need to be aware of the thing that is aware, and aware of the thing that is aware of the thing that is aware, etc, down to infinite regress.

But that doesn't necessarily mean that it's impossible. It would suggest that such a being works by moving along a set of fixed point. Suppose x is the state of the physical mind (whether that's a brain, a set of chips, or something else). Suppose f(x) returns the updated state after this mind takes into account what it knows (i.e. f(first-order aware) = first- and second-order aware). Then if the mind-state always changes so that x is a fixed point of f, then the mind already knows all there is to know about itself.

So the question, on the mind side, is whether there exists a sufficiently generally intelligent type of mind for which moving along fixed points is computationally easy. I don't know. It could be possible, it could be impossible. Finding fixed points is hard in general, though.

There's also the problem of sensors, which may seem simpler but hides a similar difficulty. What happens if whatever thing that measures blood sugar fails? Or if the immune system goes auto-immune due to an immune cell defect that makes it report benign cells as foreign? Then you need an integrity sensor for the sensors - then you need an integrity sensor for the integrity sensor... At least this fixed-point problem for sensors should be easier than the one for general minds.

The consciousness:complexity ratio would probably express itself in that a mind of a certain complexity with the fixed-point-of-f constraint would be less intelligent on average than a mind of the same complexity without such a constraint.