Electric Unicycles haven’t appeared on the radar of law makers in most countries so we only know of one country (Switzerland) where laws were specifically written with them in mind.
In most other countries they would fall in the category of engine driven means of transport (sometimes called “mechanically propelled vehicle”) and then it is possible that registration, insurance, tax and also a license for using an electric unicycle are required.
Please check your local laws for further details.
We are of the opinion that they should be treated like bicycles, possibly electric bicycles. The speed is very comparable to bicycles, the footprint is even smaller than for a bike and they use the same amount and type of energy as E-Bikes. If you have an opportunity to lobby law makers, please do so and if you need support, we are more than happy to provide you with further information.