Trying to add dither to shader with vertex color

I attempted to write an unlit shader that has vertex color using dither to deal with color banding issues. I followed t$$anonymous$$s tutorial: https://startupfreakgame.com/2017/01/15/screen-space-gradient-shader-with-dithering-in-unity/

Here is the code I came up with:

 Shader "Unlit/TEST"
 {
     Properties
     {
         _Color ("Main Color", Color) = (0.5,0.5,0.5,1)
         _NoiseTex ("Noise Texture", 2D) = "w$$anonymous$$te" {}
     }
     
     Subshader
     {
         Tags { "RenderType"="Opaque" }
         
         Pass
         {
             Tags { "LightMode" = "Always" }
             
             CGPROGRAM
                 #pragma vertex vert
                 #pragma fragment frag
                 #pragma fragmentoption ARB_precision_$$anonymous$$nt_fastest
                 #include "UnityCG.cginc"
 
                 struct appdata {
                     float4 vertex : POSITION;
                     fixed4 color : COLOR;
                     float3 normal : NORMAL;
                 };
 
                 struct v2f
                 {
                     float4 pos    : SV_POSITION;
                     float2 uv    : TEXCOORD0;
                     fixed4 color : COLOR;
                 };
                 
                 v2f vert (appdata v)
                 {
                     v2f o;
                     o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
                     o.color = v.color;
                     return o;
                 }
 
                 uniform float4 _Color;
                 uniform sampler2D _NoiseTex;
 
                 float3 getNoise(float2 uv) 
                 {
                     float3 noise = tex2D(_NoiseTex, uv * 100 + _Time * 50);
                     noise = mad(noise, 2.0, -0.5);
                     return noise/255;
                 }
                 
                 fixed4 frag (v2f i) : COLOR
                 {
                     i.color.rgb += getNoise(i.uv);
                     return _Color * 2.0 * i.color;
                 }
             ENDCG
         }
     }
     
     Fallback "VertexLit"
 }

What t$$anonymous$$s does is it gets the random value from the blue noise map, but it effects the color of the entire mesh rather than each individual pixel. I've searched the far reaches of the internet and can't seem to find a way to get t$$anonymous$$s working. I'm a noob with shaders, and any help is appreciated.