how to dynamic create a prefabs from existing sprite (png file)

i have an issue that have alot of assets of png files a.k.a sprite that loaded into the unity project i try build small tool that will load a from them a prefabs (have more then 30 and it is a pain create prefab each of them and they may change) i build this code:

   void GeneratorPrefab(AssetSpriteObject assetSprite)
             {
                 GameObject obj = new GameObject();
                 obj.name = assetSprite.Name;
                 Sprite sprite = new Sprite();
                 string spritePath = assetSprite.RelativePath.Replace(".png", "");
     
                 Debug.Log(String.Format("Loading Res {0}", spritePath));
                 sprite = Resources.Load<Sprite>(spritePath);
                 obj.AddComponent<SpriteRenderer>();
                 SpriteRenderer SR = obj.GetComponent<SpriteRenderer>();
                 SR.sprite = sprite;
     
                 String pathString = Path.GetFullPath(new Uri(Path.Combine(Path.GetDirectoryName(globalPath), String.Format(@"../../Assets/Prefabs/Gen/{0}", prefixName))).AbsolutePath);
                 if (!Directory.Exists(pathString))
                     Directory.CreateDirectory(pathString);
                 UnityEngine.Object prefab = PrefabUtility.CreateEmptyPrefab(String.Format(@"Assets/Prefabs/Gen/{0}/{0}_{1}.prefab", prefixName, assetSprite.Name.Replace(".png", "")));
                 PrefabUtility.ReplacePrefab(obj, prefab, ReplacePrefabOptions.ReplaceNameBased);
                 DestroyImmediate(obj);
             }
 

now it create the prefab but it without a sprite like the code "sprite = Resources.Load(spritePath);" if i debug i see at as null and don't understand why or how to fix my question what i do wrong here P.S the link for the source file here