I have modify to update this plugin https://github.com/hildogjr/kicad_jlcpcba/ that works directly on Pcbnew/KiCad 5.99 to create the BOM and position files (using less libraries as possible and fixing the rotation), that will not need scrape the design files (Python API get all information).
But it don’t automatically populate the Manufacture Part Numbers. Maybe we could merge such functionalities to have a friendly plugin for v6.