This is very cool! What is the practical intent, given USB ports are 69c each? To save vertical space? I am thinking: Neat this is elegant and would work! But I can't think of any scenarios (off-the-cuff.) where I would choose this.

I made it for a business card, the whole card, PCB and components together, is 1.6 mm thick! That was my motivation for this

I have no idea how easy it is to implement this in KiCAD, but if it is - prototyping with this can be faster if you're eg making something like a DIY keyboard. Fewer things to solder, which is very nice if you struggle with it.

It is as easy as 123, just a couple of clicks, and its all explained on the GitHub. However, unless you're committing to a 0.6 mm PCB, I wouldn't really use this on a keyboard, especially a full size one. The board really is not rigid at those sizes at that thickness. Weigh a tradeoffs and use it if it works for you!