Modern electric unicycle no need any special winter preparation.
Yet, the battery life decreases faster at lower temperature. Li-ion batteries can not charge at a temperatures below zero.
Always store and recharge the battery in a heated room. When riding, the battery generates heat as a result of energy loss. Therefor, most of the li-ion devices are safe at 0-10 °C.
In most of the winter conditions, the stock tire will work good enough. It worth consider a tire change to the one which is suitable for snow or slush. Winter tire greater rolling resistance may reduce the range. Studs may not work well on concrete.
Winter rides demanding more care of your unicycle. Road salt will cause corrosion on any metal parts of the unicycle. You have to clean it and treat all exposed mechanics with fat and oil.