How do I make an object visible behind walls in unity?

Question

I am trying to make my player visible as a certain color behind walls in unity, here is the shader I have :

Shader "N3K/Player"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Color("BehindWallColor",Color) = (0,0,0,0)
    }
    SubShader
    {
        Tags {"Queue"="Transparent"}
        LOD 100
        Pass
        {
            Cull Off
            ZWrite Off
            ZTest Always
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
            };

            struct v2f
            {
                float4 vertex : SV_POSITION;
            };

            float4 _Color;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                return _Color;
            }

            ENDCG
        }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uv);
                return col;
            }
            ENDCG
        }
    }
}

this works but the object has no shadow now as ig it is semi transparent, is there any other way to do this while also making the object cast shadows? and how can I specify which objects is the player rendered behind and which are not?