How to pick a texture from device folder?

Hello, I'm new to Unity. I want that a png file saved in the device should be picked and set as the texture. I searched a found a suggestion shown here:

  public static Texture2D LoadPNG(string filePath) {
  
      Texture2D tex = null;
      byte[] fileData;
  
      if (File.Exists(filePath))     {
          fileData = File.ReadAllBytes(filePath);
          tex = new Texture2D(2, 2);
          tex.LoadImage(fileData); //..this will auto-resize the texture dimensions.
      }
      return tex;
  }

This looks great but how a path is assigned to string variable so that it selects the device folder. Thanks