Convert blender materials to pixel shadeless

mtl_pixel.py

import bpy

## For materials that have an image and a principled bsdf (like .obj imports fo instance)
## it will re-connect and set up everything to pixely emission with binary alpha
## IMPORTANT
## it will fuck up everything else that has an image texture and bsdf
## add some if's that make sence in your case

for mat in bpy.data.materials:
    try:
        mat.blend_method = 'CLIP'
        mat.use_backface_culling = True
        
        nt = mat.node_tree
        img = nt.nodes['Image Texture']
        bsdf = nt.nodes['Principled BSDF']
        
        img.interpolation = 'Closest'
        
        nt.links.remove(img.outputs['Color'].links[0])
        nt.links.new(img.outputs['Color'], bsdf.inputs['Emission'])
        nt.links.new(img.outputs['Alpha'], bsdf.inputs['Alpha'])
        
        bsdf.inputs['Base Color'].default_value = (0, 0, 0, 0)
    except:
        pass