Reading from Depth Texture in Unity 2021.1.7f1

I began making this project that has many similarities to Sebastian Lague's "Atmosphere" coding adventure, so I decided to take inspiration from one of his shaders. The link is here (specifically minute 2:01). This video was published last year, so as I expected I ran into difficulties when sampling from the depth texture. After hours of reading documentation, I decided to simply check if I could display the plain depth texture without any post processing effects like so:

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

         struct v2f
         {
             float2 uv : TEXCOORD0;
             float4 vertex : SV_POSITION;
             float3 viewVector : TEXCOORD1;
             float2 depth : TEXCOORD2;
             
         };

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

             float3 viewVector = mul(unity_CameraInvProjection, float4(v.uv.xy * 2 - 1,0,-1));
             o.viewVector = mul(unity_CameraToWorld, float4(viewVector,0));

             UNITY_TRANSFER_DEPTH(o.depth);

             return o;
         }

         sampler2D _MainTex;

         float3 planetCenter;
         float atmosphereRadius;
         float planetRadius;

         fixed4 frag (v2f i) : SV_Target
         {
             
             //fixed4 col = tex2D(_MainTex, i.uv);
             
             return float4(Linear01Depth(i.depth),0,0,1);
             

             
         }
         ENDCG

With this I got a black screen as a result and an error that said Metal: Error creating pipeline state (Custom/AtmosphereShader): Link failed: fragment input user(TEXCOORD2) was not found in vertex shader outputs (null). I got these commands from the unity documentation here. So then I tried going even simpler and taking the code from the documentation that supposedly renders the depth from objects in the scene:

 Shader "Render Depth" {
 SubShader {
     Tags { "RenderType"="Opaque" }
     Pass {
         CGPROGRAM

         #pragma vertex vert
         #pragma fragment frag
         #include "UnityCG.cginc"

         struct v2f {
             float4 pos : SV_POSITION;
             float2 depth : TEXCOORD0;
         };

         v2f vert (appdata_base v) {
             v2f o;
             o.pos = UnityObjectToClipPos(v.vertex);
             UNITY_TRANSFER_DEPTH(o.depth);
             return o;
         }

         half4 frag(v2f i) : SV_Target {
             UNITY_OUTPUT_DEPTH(i.depth);
         }
         ENDCG
     }
 }

}

Though there wasn't an error, the black screen prevailed. the program on my camera that blits the shader is really simple it's just:

  using UnityEngine;
  [ExecuteInEditMode]
  public class PPCamera : MonoBehaviour
   {

 public Material postProcessingMat;


 void OnRenderImage(RenderTexture source, RenderTexture dest){

     Graphics.Blit(source,dest,postProcessingMat);

 }

}

I'm new to shaders so I may be missing something very obvious but does anyone know any workarounds?