Freewheel unicycle hub?

It’s hard to see detailed information but it looks there is a custom method to attach the fork to the hub which may be along the lines of this 3.8x geared drift drift trike that is not quite for sale yet. I like that there are three shiftable gears but it needs a disc brake to be an effective freewheel unicycle. I also would prefer a smaller wheel for mountain unicycling since I’m on the short side.