SUP indoor trainer

I came across this review of a German SUP indoor trainer.

it looks like it would train balance and the appropriate muscles nicely.

Does anyone know of a similar device sold in the US? Does anyone have experience with similar devices?

I found some complex machine SUP trainers and think the above simple board on a round pole makes more sense. Looks like it can be built DIY, but if a nice one can be bought, that would be good.

A little plywood and paint and some 4" PVC and you’d be in business.