reference objects without materials We are making our thesis film on maya for the rigging options, and prefer blender for the render, amongst other things because we want multilighting with ramp shaders. Our problem is that we want to animate parts of the background witout having to reassign shaders for each file. 

So we came up with a solution. Import the animation in alembic from maya into blender, save the file, open a new file and then link the objects from the previous file, then add overrides and create materials.
The idea would be to swap alembic files in the original file; and in the new file, have an updated version with the shader overrides. 

The problem is that when we try that, the file does update, but the new shaders are gone. 

I found this video that looks a bit like what we'd want, but it's for visibility, not materials. https://theduckcow.com/2018/blender-overrides/

Thanks in advance ! 

EDIT: here's a simplified version of what we achieved in blender, and that would be less easily achievable in maya.
OKAY ! So finally, after playing around with various scripts found on this website, assembling them, we found out  we had taken it the wrong way, as blender workflow is different from maya. The material is applied after in maya, and before in blender. 
The solution is a simple script that asks objects from the scene to be applied a premade material. In maya, naming is important for referencing, so our objects always have the same name. It's a bit fastidious to enter each name individually the first time, but it works out for us, as we simply run the script for each panel thereafter.

Here's our frankenbaby: (replace lama with whatever name you have)

import bpy
ob = bpy.data.objects.get("lama")

# Get material
mat = bpy.data.materials.get("Lamamat")
if mat is None:
    # create material
    mat = bpy.data.materials.new(name="Lamamat")

# Assign it to object
if ob.data.materials:
    # assign to 1st material slot
    ob.data.materials[0] = mat
else:
    # no slots
    ob.data.materials.append(mat)