Custom AR Camera Background material

I’m trying to get a shader together for a custom AR camera background material. I would like to be able to change in particular the brightness of the live camera view.
I tried a simple shader with a _MainTex property (as this seems to be a standard) and also _textureY (which I got from some online sources) as the name of the texture.
I’m iusing URP.
Exampe code below.

Can anyone help pls.

Shader "Custom/UnlitColorAdjust_forARBackground"
{
    Properties
    {
        _textureY ("_textureY", 2D) = "white" {}
       //_MainTex ("Texture", 2D) = "white" {}
        _Hue ("Hue", Range(-360, 360)) = 0.
        _Brightness ("Brightness", Range(-1, 1)) = 0.
        _Contrast("Contrast", Range(0, 2)) = 1
        _Saturation("Saturation", Range(0, 2)) = 1
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100
        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 _textureY;
            float4 _textureY_ST;
            float _Hue;
            float _Brightness;
            float _Contrast;
            float _Saturation;
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _textureY);
                return o;
            }
            inline float3 applyHue(float3 aColor, float aHue)
            {
                float angle = radians(aHue);
                float3 k = float3(0.57735, 0.57735, 0.57735);
                float cosAngle = cos(angle);
                //Rodrigues' rotation formula
                return aColor * cosAngle + cross(k, aColor) * sin(angle) + k * dot(k, aColor) * (1 - cosAngle);
            }
            inline float4 applyHSBEffect(float4 startColor)
            {
                float4 outputColor = startColor;
                outputColor.rgb = applyHue(outputColor.rgb, _Hue);
                outputColor.rgb = (outputColor.rgb - 0.5f) * (_Contrast)+0.5f;
                outputColor.rgb = outputColor.rgb + _Brightness;
                float3 intensity = dot(outputColor.rgb, float3(0.299, 0.587, 0.114));
                outputColor.rgb = lerp(intensity, outputColor.rgb, _Saturation);
                return outputColor;
            }
            fixed4 frag (v2f i) : SV_Target
            {
                float4 startColor = tex2D(_textureY, i.uv);
                float4 hsbColor = applyHSBEffect(startColor);
                return hsbColor;
            }
            ENDCG
        }
    }
}

Please reference the source for the ARCore (for Android) or the ARKit (for iOS) camera background shader that are included in the respective provider packages.