I never made a concrete claim that consciousness is located in a specific brain region. I speculated that, but the truth is we don't know if it's one sub-region which represents consciousness, or a combination of many.
As for "how it interfaces with the purported non conscious parts of the body", this part is incredibly obvious. Afferent nerves take information from sensory receptors into the brain, and efferent neurons transport motor signals from the brain to the muscles.
There's no mystery at all about the interface: if consciousness is a product of some sub-region of the brain, the interface is the set of synapses carrying information into and out of that region.
> it is too big of a leap to claim that a locale that is not even the whole brain is essential to consciousness.
I would argue the evidence is incredibly strong that consciousness is localized at least within the brain, if not within a more specialized subset of the brain. Basically every intervention we know about which is capable of having a profound effect on consciousness has to act on the brain. You can amputate an arm or a leg, and consciousness remains intact. However psychoactive drugs interfering with normal activity at the synapse, and trauma to the tissue of the brain causes reliable and repeatable effects on consciousness. If consciousness is indeed a property which originates outside the brain as well, why is it that we can only affect it by taking physical action at the brain itself?
As for the argument that it's not "the whole brain", there's a lot of evidence for that as well. For instance, people with various forms of brain damage can lose certain functions without losing consciousness. For instance, people with lesions in the primary visual cortex may not be able to see, but they surely retain their consciousness and subjective experience.
> ...embodied cognition. There are cool experiments like people’s cognitive skills diminishing when they are prevented from making hand gestures.
This one is very easy to explain and there's no revelation there. Basically all of psychology research has shown that if you divide someone's attention, they perform worse on cognitive tasks. If you artificially require someone to restrict their hand movement, they must spend some of their cognitive capacity thinking about their hands, so they're going to do worse at everything else relative to baseline. If this didn't happen, it would be extremely shocking.