You would be incorrect https://en.m.wikipedia.org/wiki/Neuroglycopenia if your blood glucose levels dropped to 0, you would die pretty rapidly. It’s analogous to unmanaged Type 1 diabetes in a vague sense.
There is no physiological requirement for dietary carbohydrates. There is a requirement for glucose, but your body can create it from non-carbohydrate sources including the acetone produced by ketones. https://en.m.wikipedia.org/wiki/Gluconeogenesis