I just referenced the Tallbike site, it is gone unfortunately. The owner was in Vietnam and had some interesting prototypes completed. A long list of prospective clients but things were just not getting to the production stage from my observance. He was working on variations of main wheel diameter and some variations of pedal action. I would have just got one into the delivery mode.

Anyone know what happened?

As to getting one, I would attempt to test ride one, the biomechanics of starting and stopping are very different. The threat of going over the top is quite real, braking is more like a controlled deceleration.
It can be done, and of course was done, I have watched riders of them and it would be helmet time for me… maybe even with an attached face guard.

I would go for a bit later in time and one of the early "safety" bikes. Still direct drive, no brakes essentially, solid tires.