Exactly, and even if nobody has ever built it or written a formal proof that it would work, you can still imagine how it would work and prove it to your own mind.
(This would work for a purely mechanical computer made out of rocks, too.)
Personally, with enough knowledge about how modern AI works, and a reasonable understanding of the neuroscience literature, I feel there is no fundamental mystery to consciousness, only awe at the level of complexity harnessed.