Unity Universal Render Pipeline MatCap shader that also looks nice on flat surfaces.

MatCapImproved.shader

Shader "Custom/MatCapImproved"
{
    Properties
    {
        [NoScaleOffset] _MainTex("MatCap", 2D) = "black" {}
        _ViewDirBlend("View direction blend", Range(0,1)) = 0
    }

    SubShader
    {
        Tags
        {
            "RenderType" = "Opaque"
            "RenderPipeline" = "UniversalRenderPipeline"
        }

        Pass
        {
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"            

            TEXTURE2D(_MainTex);
            SAMPLER(sampler_MainTex);
            real _ViewDirBlend;

            struct Attributes
            {
                real3 positionOS : POSITION;                 
                real3 normalOS : NORMAL;                 
            };

            struct Varyings
            {
                real4 positionHCS : SV_POSITION;
                real2 uv : TEXCOORD0;
            };            

            Varyings vert(Attributes IN)
            {
                Varyings OUT;
                OUT.positionHCS = TransformObjectToHClip(IN.positionOS);

                real3x3 objectToViewMatrix = (real3x3)
                    mul(GetObjectToWorldMatrix(), GetWorldToViewMatrix());

                real3 uvw = IN.normalOS;
                //This one line adds the view direction dependency
                uvw += SafeNormalize(IN.positionOS) * _ViewDirBlend;
                uvw = normalize(mul(objectToViewMatrix, uvw));

                //Remap from [-1, 1] to [0, 1]
                OUT.uv = uvw.xy * .5 + .5;
                return OUT;
            }

            real4 frag(Varyings IN) : SV_Target
            {
                return SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, IN.uv);
            }
            ENDHLSL
        }
    }
}