See https://forums.dfworkshop.net/viewtopic.php?p=27184#p27184 for Kaedius' helpful post I have reproduced here. This info enabled me to add the Archeologists Guild ...
The goal is to create a Blender & Unity plugin that makes importing content from Blender to Unity seamless & easy. This will be achieved by exporting a .ublend (UnityBlender) file format, a JSON file ...