Creates a duplicate of the scene containing only instances

full-linked-copy-of-scene.py

import bpy

def full_linked_copy_scene():
    scene_copy = bpy.data.scenes.new(bpy.context.scene.name + ' - Full Linked Copy')
    
    # https://blender.stackexchange.com/a/167889/38603
    collections_in_scene = [
        c for c in bpy.data.collections 
            if bpy.context.scene.user_of_id(c)
    ]

    # duplicate all collections
    for c in collections_in_scene:
        collection_copy = bpy.data.collections.new(c.name + ' - Copy')
        scene_copy.collection.children.link(collection_copy)
        # make instances of all objects in the collection
        for o in c.objects:
            if o.parent == None:
                instance_recursive(o, collection_copy)

    return None

def instance_recursive(original_object, target_collection):
    instance = original_object.copy()
    instance.name = original_object.name + ' - Instance'
    target_collection.objects.link(instance)
    # not sure why I have to set this...
    instance.hide_viewport = False

    if len(original_object.children) > 0:
        for c in original_object.children:
            i = instance_recursive(c, target_collection)
            i.parent = instance
            
    return instance

# ensure that every instance can have their own materials
for o in bpy.data.objects:
    if o.type == 'MESH':
        for s in o.material_slots:
            # need to back up the material first, because Blender UX is as always awful
            m = s.material
            s.link = 'OBJECT'
            s.material = m

full_linked_copy_scene()