Blender - Copy BSDF specular to all material slots

import bpy

for obj in bpy.context.selected_objects:
    if obj.type == 'MESH':
        for slot in obj.material_slots:
            # Check if the material has a node tree
            if slot.material and slot.material.node_tree:
                principled_node = slot.material.node_tree.nodes.get("Principled BSDF")

                if principled_node:
                    # Set values for the Principled BSDF shader
                    principled_node.inputs[2].default_value = 1  # Roughness
                    principled_node.inputs[1].default_value = 1  # Metallic