import os
import bpy


### INSERT BASE PATH ###
base_path = ""

dirs = os.listdir(base_path)

for dir in dirs:
    dir_path = os.path.join(base_path, dir)
    spec_dirs = [os.path.join(dir_path, f) for f in os.listdir(dir_path) if os.path.isfile(os.path.join(dir_path,f))]

    for filepath in spec_dirs:
        with bpy.data.libraries.load(filepath, link=False) as (data_from, data_to):
            data_to.materials = data_from.materials