I have done something similar before using morph targets (origami), but this looks like it could be done with simple IK. Parent the IK handle to the bone of the page that opens (green). Rotating that bone then pulls on the joint chain for the popup section. Parent the root bone of the popup section to the other bone.
I tried @kwyjibo's way in Blender, it does work. For elements that need to open perpendicular to the pages (like in your photos with real paper), you can lay the bones on the pages. I also needed to tick "lock X axis" in the IK settings so those bones would always stay on the pages and not move away from them (the IK…