UnityExporter.py

import bpy
import math
import os

for obj in bpy.context.selected_objects:
    obj.rotation_euler[0] = math.radians(-90)
    bpy.ops.object.transform_apply()
    obj.rotation_euler[0] = math.radians(90)

path = bpy.path.abspath("//") # .blend existing path
name = bpy.context.active_object.name_full
dst = path + name
#bpy.ops.export_scene.gltf(filepath = dst + '.glb', use_selection = True)
bpy.ops.export_scene.fbx(filepath = dst + '.fbx', use_selection = True, apply_scale_options = 'FBX_SCALE_ALL', use_armature_deform_only = True)

for obj in bpy.context.selected_objects:
    bpy.ops.object.transform_apply()