But if I am truly relaxed in all those areas, and not just squishing into a bag of bones of the floor, then something is holding me up.
Exactly. If you are going to push something, it requires strength, so the question is whether you use muscular strength or 'internal strength' (whatever that is). If you are going to use strength, you must have structure of some kind; the question how that structure is formed and what it's composed of: normal body mechanics or the body mechanics of 'internal strength' (whatever that is).
Your diagrams appear to be roughly about structure rather than how the strength is generated, but the question is about what and how that structure is being held together and how it functions.
For all practical purposes your diagrams could be considered oddly-shaped brackets (like the bracket that holds up a bookshelf on the wall). The question is about getting the force from the bottom of the right-side black line to the tip of the left-side black line. The ideal force would go straight from one to the other, so the body, regardless of its shape should act mainly as a frame that conveys the shortest, strongest practicable force from foot to hand.
How to hold the frame together so that it is strong but flexible? That's what breathing exercises are for.