Example of how to make your shader accessible in C#.

GridShader.cs

using UnityEngine;

/** This class communicates directly with the shader to draw grids. The shader's 
    properties look like this:

Shader "SDF/Grid"{
  Properties{
    [KeywordEnum(Grid, Cross, Ticks)]
    _GridKind ("Kind", Int) = 0
    _InsideColor("Inside Color", Color) = (.5, 0, 0, 1)
    _OutsideColor("Outside Color", Color) = (0, .5, 0, 1)
    _LineThickness("Major Line Thickness", Range(0, 0.1)) = 0.05
    // _LineDistance("Major Line Distance", Range(0, 1)) = 0.1
    _SubLineThickness("Proportion thickness of in between lines", Range(0, 1)) = 0.25
    [IntRange] _SubLines("Number of lines between major lines", Range(0, 9)) = 1
    _Offset("Offset", Vector) = (0, 0, 0, 0)
    _LineDistance("Major Line Distance", Vector) = (1, 1, 0.05, 0.05)
  }
*/
public class GridShader {
  public enum Kind {
    Grid = 0,
    Cross,
    Ticks
  }

  public class PropertyID {
    public int gridKind;
    public int insideColor;
    public int outsideColor;
    public int lineThickness;
    public int lineDistance;
    public int subLineThickness;
    public int subLines;
    public int offset;
  }

  /** We only need to get the properties once. */
  private static PropertyID _propertyID;
  public static PropertyID propertyID {
    get {
      if (_propertyID == null) {
        _propertyID = new PropertyID {
          gridKind = Shader.PropertyToID("_GridKind"),
          insideColor = Shader.PropertyToID("_InsideColor"),
          outsideColor = Shader.PropertyToID("_OutsideColor"),
          lineThickness = Shader.PropertyToID("_LineThickness"),
          lineDistance = Shader.PropertyToID("_LineDistance"),
          subLineThickness = Shader.PropertyToID("_SubLineThickness"),
          subLines = Shader.PropertyToID("_SubLines"),
          offset = Shader.PropertyToID("_Offset")
        };
      }
      return _propertyID;
    }
  }

  // protected MaterialPropertyBlock material;

  // public GridShader(MaterialPropertyBlock material) {
  //   this.material = material;
  // }
  protected Material material;

  public GridShader(Material material) {
    this.material = material;
  }

  public Color insideColor {
    get => material.GetColor(propertyID.insideColor);
    set => material.SetColor(propertyID.insideColor, value);
  }

  public Color outsideColor {
    get => material.GetColor(propertyID.outsideColor);
    set => material.SetColor(propertyID.outsideColor, value);
  }

  public float lineThickness {
    get => material.GetFloat(propertyID.lineThickness);
    set => material.SetFloat(propertyID.lineThickness, value);
  }

  public Vector4 lineDistance {
    get => material.GetVector(propertyID.lineDistance);
    set => material.SetVector(propertyID.lineDistance, value);
  }

  public float subLineThickness {
    get => material.GetFloat(propertyID.subLineThickness);
    set => material.SetFloat(propertyID.subLineThickness, value);
  }

  public int subLines {
    get => material.GetInt(propertyID.subLines);
    set => material.SetInt(propertyID.subLines, value);
  }

  public Vector4 offset {
    get => material.GetVector(propertyID.offset);
    set => material.SetVector(propertyID.offset, value);
  }

  // public static Kind GetKind(Material material)
  //   => (Kind) material.GetInt("_GridKind");
  // public static void SetKind(Material material, Kind value) {
  //   EnableKeyword(material, "_GRIDKIND_GRID", value == Kind.Grid);
  //   EnableKeyword(material, "_GRIDKIND_CROSS", value == Kind.Cross);
  //   EnableKeyword(material, "_GRIDKIND_TICKS", value == Kind.Ticks);
  // }

  /** Enable or disable a shader keyword based on a boolean value. */
  static void EnableKeyword(/* this */ Material material, string keyword, bool enable) {
    if (enable)
      material.EnableKeyword(keyword);
    else
      material.DisableKeyword(keyword);
  }

  // Would like to do this but can't do it with a material block.
  public Kind kind {
    get => (Kind) material.GetInt("_GridKind");
    set {
      EnableKeyword(material, "_GRIDKIND_GRID",  value == Kind.Grid);
      EnableKeyword(material, "_GRIDKIND_CROSS", value == Kind.Cross);
      EnableKeyword(material, "_GRIDKIND_TICKS", value == Kind.Ticks);
    }
  }
}