Hackaday featured an electric skateboard on 3 wheels by swedishFeetballs, using some unique components:
The build relies on a large combined hub motor and wheel, similar to those you would find on a hoverboard or some electric scooters; this one is a Xiaomi part sourced from eBay. It’s controlled via an off-the-shelf electric skateboard speed controller that comes complete with its own remote.
The hardware is all bolted up to a custom skateboard deck built from scratch to accept the large single rear wheel. Up front, a regular skateboard truck is used. Batteries are mounted under the deck. Reportedly, the board has a top speed of 15 mph, which unsurprisingly matches that of the Xiaomi M365 the hub motor is sourced from.
The only footage available is above and if you want to try making it yourself, check out its Instructables page.