Someone linked the "parallel to the wall" hanger here https://www.amazon.ca/Retractable-Adjustable-Wardrobe-Clothi... and it costs a lot. If you want to put multiple ones next to each other, it becomes quite expensive.

Also access to items behind other items becomes harder and slower. And it requires a shelf above to secure to.

Horizontal pole and foldable hanger design still seems like a simpler and better approach. The design seems so good that I bet you will be able to order these from China in a couple of years for less than a dollar.

So I've thought about the problem some more, and have my own idea.

You would still have a rod mounted a short distance from the wall, like the clothes hinger design, but a little further out. The rod for the clothes hinger has grooves that are perpendicular to the long axis of the rod.

But what if you cut the grooves at an angle instead, maybe 60 degrees. This would take up about the same distance out from the wall as the clothes hinger design, but slightly more wall space. This would be a factor for very constrained walls, but for the longer rods, the "overhead" would be insignificant. And it would only project out from the wall the same as the clothes hinger design (that's trigonometry!).

You would use a smaller diameter rod, so that with the grooves cut at an angle, the diameter is still sufficiently small enough to use a regular clothes hanger.