Sprite _newSprite = Sprite.Create(Texture, Rect);

public List<Sprite> _spriteList;//Сюда пихаешь спрайты через инспектор
Dictionary<string, Sprite> _spriteDictionary = new Dictionary<string, Sprite>();

void Start()
{
foreach(var item in _spriteList)
{
if(!_spriteDictionary.ContainsKey(item.name))
{
_spriteDictionary.Add(item.name, item);
}
}

public Sprite GetSprite(string _name)//тут вытягиваешь по имени спрайта
{
return (_spriteDictionary.ContainsKey(_name))? _spriteDictionary[_name]: null;
}

Shader "Custom/MainShader" {
    Properties {
  _MainTex ("Albedo (RGB)", 2D) = "white" {}
  _MainTex2 ("Mask (RGB)", 2D) = "white" {}
  _Value ("Value", Range(0,1)) = 0.0
    }
    SubShader {
  Tags
  {
   "Queue"="Transparent"
   "IgnoreProjector"="True"
   "RenderType"="Transparent"
   "PreviewType"="Plane"
   "CanUseSpriteAtlas"="True"
  }

  CGPROGRAM

  #pragma surface surf Standard fullforwardshadows

  sampler2D _MainTex;
  sampler2D _MainTex2;
  half _Value;

  struct Input
  {
   float2 uv_MainTex;
   float2 uv_MainTex2;
  };

  void surf (Input IN, inout SurfaceOutputStandard o)
  {
   fixed4 c = tex2D (_MainTex, IN.uv_MainTex);
   fixed4 m = tex2D (_MainTex2, IN.uv_MainTex2);

   o.Albedo = lerp(c,m,_Value);
   o.Alpha = c.a;
  }

  ENDCG
    }
    FallBack "Diffuse"