I wish to add a new scene export format for Paraview. Is this something that can be done via a Python/C++ plugin for Paraview or do I have to make the change at the Paraview source code level and do a full recompile and packaging/deploy ?
I am definitely not one to have an answer for this, but I can point you to a Python script for vtk.js that will export ParaView data scenes. I imagine it might be possible to make a new Python plugin in PV v5.6 that could export an entire data scene.
The mentioned export script is found on this page and the actual raw script is here