Qt for Python (PySide/Shiboken)

If this is rendered in a qml scene, and this isn't two native windows overlayed, but it's combined and rendered on the same surface (we're getting on the edge of my understanding of how the Scene Graph and Qt RHI works, so this may not be completely accurate), you may be able to copy the contents of the surface to an offscreen surface and QOpenGLFramebufferObject, and from that get the pixel result... But, getting this in Python is definitely going to need some C++.