By public demand I put together the current state of our migration code for the University Gent:
https://public.zopyx.com/ugent.plone5migration.zip
The PFG -> EasyForm migration is located in the file pfg.py.
Also already mentioned the code is based on our approach using collective.jsonify for the export, ArangoDB inbetween as migration database and our "magic" migration script for the import over plone.restapi. The magic migration script is also included...
Use the stuff at your own risk...I will talk about this migration project at the Plone conference in Ferrara.