>>302086973
You can unpack the prefab and pull apart the individual gameObjects if it want, and I think the mesh references will update properly when you update the original .blend.

My workflow is to make individual models of props in blender and not worry about the scale too much, just roughly 1 blender unit = 1 meter (some people use 1 blender unit = 1cm, which is sometimes more convenient for really small props since blender's default camera front clip plane is like 5cm). Then I export the model to fbx, import in unity, scale the prefab in the unity scene however I want (and duplicate, position, rotation, etc), as well as "extract materials" in the materials tab of the importer so I can adjust that. Then when I need to adjust the mesh, or UVs or vertex colors, I use blender, export the FBX, then unity will detect the changed file and update the scene in real-time. So like your imagined work flow, but only one way.