bigknockdown Hi! Very sorry for the late reply!
What I would do in this case, would be to have the prefab modules already made and packed in the addressable packages.
The download and unpack would be a scene happening before Home Designer scenes. once everything is downloaded, I would rebuild the module list (skipping the json) and fill a scriptable object at runtime with all the modules data.
Then launch the home designer scene and replace the module json reading by the scriptable object.
Not sure if that answering your question so let me know if I misunderstood.