List .blend library collections by python (append material from another .blend file)

Hi Blenderers!

I would like to load material from another .blend file in python.
I can do the following:

materialName = 'BMD_Gold_0001'
filepath = "/home/Downloads/1-gold.blend\\Material\\"
bpy.ops.wm.append(filename = materialName, directory = filepath)

It works fine but it requires the material name in the directory,
I want to list all the files in “Material”, then I can load it without stating the filename.
Is there a way to list the files in Material folder?

In regular program, I would use os.listdir, but because its not a regular directory and it gets access through .blend file so I can’t do it.