I've tried all the setups at this point, including the supine one. It has plenty to recommend it in a limited, mostly consumptive role; many people sleep a whole eight hours in roughly that position. It does tend to get in the way of typing although a fully split keyboard can address that.

But my everyday work is now done at a floor table. This posture brings a different level of activation energy, and it lets me keep moving around which is a clear advantage over most. It can present some of the same stresses as chair seating but it has more opportunities to relax. And unlike the standing or treadmill desks it easily works on a budget too - tape up a cardboard box and weigh it down and you have a temporary desk setup that will support most equipment. For a better surface with a finish and leg room, Ikea provides options, or you can get more specialized folding floor desks with angle adjustments and drawers off of Amazon.