Point all bones up (z-axis) to "Normalize" them. This will mean when imported into Unity their rotations should all be euler (0, 0, 0). This is for apps like Warudo or VMC so you can preserve your workflow without having to use an in-Unity script.

NormalizeBones.py

bl_info = {
    "name": "Normalize bones",
    "blender": (3, 4, 1),
    "category": "Object",
}

import bpy
import mathutils

class NormalizeBonesOperator(bpy.types.Operator):
    
    bl_idname = "object.normalizebones"
    bl_label = "Normalize bones"
    bl_description ="Point all bones along the same axis"
    bl_options = {'REGISTER', 'UNDO'}
    
    def execute(self, context):        
        for target in bpy.context.selected_objects:
            bpy.ops.object.mode_set(mode = 'EDIT')
            if target.type == 'ARMATURE':
                print(target.name)
                for b in target.data.edit_bones:
                    b.use_connect = False
                for b in target.data.edit_bones:
                    b.use_inherit_rotation = False
                    b.use_local_location = False
                    b.use_relative_parent = False
                    b.tail = b.head + mathutils.Vector((0.0,0.0,b.length))
                    b.roll = 0.0
            bpy.ops.object.mode_set(mode = 'OBJECT')
        
        return {'FINISHED'}
    
    def invoke(self, context, event):
        return self.execute(context) 

def menu_func(self, context):
    self.layout.operator(NormalizeBonesOperator.bl_idname)

def register():
    bpy.utils.register_class(NormalizeBonesOperator)
    bpy.types.VIEW3D_MT_object.append(menu_func)

def unregister():
    bpy.utils.unregister_class(NormalizeBonesOperator)
    
if __name__ == "__main__":
    register()