Not a neuroscientist here, so this is just layman's rambling thoughts, but I wonder if that much direct communication between the brain hemispheres were actually needed to appear as a single consciousness:
As I understand it, a large part of how the brain develops is "learning" both about the environment and about the intricacies of one's own body.
There is no engineer who calibrates the brain to work with the particular weight distribution of one's arms or the particular optical properties of one's eyes. Instead, the brain "self-calibrates" through a sort of trial-and-error process (and some deep learning magic I imagine).
The two brain hemispheres are still sitting in the same skull for the entirety of one's lifetime - so even if they were not connected at all, they are still subject to the same environmental stimuli and might come to very similar "calibrations". So the appearance of a unified consciousness might come from the two hemispheres "thinking the same way", while also being subjected to the same stimuli.
As I understand it, a large part of how the brain develops is "learning" both about the environment and about the intricacies of one's own body.
There is no engineer who calibrates the brain to work with the particular weight distribution of one's arms or the particular optical properties of one's eyes. Instead, the brain "self-calibrates" through a sort of trial-and-error process (and some deep learning magic I imagine).
The two brain hemispheres are still sitting in the same skull for the entirety of one's lifetime - so even if they were not connected at all, they are still subject to the same environmental stimuli and might come to very similar "calibrations". So the appearance of a unified consciousness might come from the two hemispheres "thinking the same way", while also being subjected to the same stimuli.