Why doesn't this shader work on android

Questions & Answers
1

This shader doesn’t work on android even though it’s not that complex
What did I do wrong?

Shader "Cone/Tile" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_Wallpaper ("Wallpaper", 2D) = "white" {}
	}
	
    SubShader {
        Pass {
        	LOD 100
        
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

			uniform sampler2D _MainTex;
			uniform sampler2D _Wallpaper;
			
			struct input
			{
				float4 vertex : POSITION;
				float4 tc : TEXCOORD0;
			};
			
            struct vertOut {
                float4 pos : SV_POSITION;
                float4 scrPos;
                float2 tc;
            };

            vertOut vert(input i) {
                vertOut o;
                o.pos = mul (UNITY_MATRIX_MVP, i.vertex);
                o.scrPos = ComputeScreenPos(o.pos);
                o.tc = i.tc.xy;
                return o;
            }

            fixed4 frag(vertOut i) : COLOR0 {
                float2 wcoord = i.scrPos.xy / i.scrPos.w;
                fixed4 tex = tex2D(_MainTex, i.tc);
                return tex2D(_Wallpaper, wcoord) * (1 - tex.a) + tex * tex.a;
            }

            ENDCG
        }
    }
    
	Fallback "Unlit/Texture"
}
2

Even the simplest shader can not work at some mobile devices. So it is necessary to test on several. (if there is such opportunity). Maybe device wrong calculate screen position. But in your case there are some differences from the standard. Try the following replacements:

 struct vertOut {
  float4 pos : SV_POSITION;
  float4 tc: TEXCOORD0; //change type
  float4 scrPos;
 };

And

 vertOut vert(input i) {
  vertOut o;
  o.pos = mul (UNITY_MATRIX_MVP, i.vertex);
  o.scrPos = ComputeScreenPos(o.pos);
  o.tc = i.tc; //rigth equal
  return o;
 }

 float4 frag(vertOut i) : COLOR0 {
  float2 wcoord = (i.scrPos.xy / i.scrPos.w);
  float4 tex = tex2D(_MainTex, float2(i.tc));
  return (tex2D(_Wallpaper, wcoord) * (1 - tex.a) + tex * tex.a);
 }

I hope that it help you.