I would assume that another factor is that the technique for a given exercise on the other hand can be improved, and that can help with decreasing the necessary energy - would that be a correct statement? And as a follow up, depending on activity type this may or may not be significant?

Yes, definitely. Technique is partly about efficient mechanical movement, sending the various parts of your body in the right direction(s) and not waste effort on movement that doesn’t contribute to propelling you forwards. But for endurance sports, it’s really about minimizing energy cost at a given speed. To use running as an example, you can improve biomechanical efficiency through better timing, correct loading of tendons, tendon stiffness, elastic energy use, and more.