You’re right the ANS can influence heart rate but the heart itself has an intrinsic rate. The SA node has an intrinsic rate between 60-100bpm. The AV nice has an intrinsic rate of about 40-60bpm. The ventricles have an intrinsic rate of about 30bpm. That’s why in complete heart block often the heart rate is about 30bpm as that’s the default rate of the ventricles when signals from the SA or AV node are blocked.

Hmmm I think I would be wary putting something in the mouth of someone who is completely unconscious as they have a high risk of aspirating because they lose their protective airway reflexes.

But by all means if someone has reduced consciousness but they’re still able to swallow then we essentially use exactly that in the hospital context: a sugary gel as first line treatment of hypoglycaemia.

Unlikely to put someone into DKA by giving them sugar as it's the lack of insulin that precipitates DKA rather than excess of sugar. But otherwise agree, important not to give unconscious person food.