How to display the categories on page using shortcode?

Is there any issue with my code?

Yes, there is. get_categories() returns an array of terms, e.g. WP_Term objects or a list of term IDs, so you can’t simply do return $categories;.

Instead,

• For a basic list such as Foo category, Bar category, etc. (i.e. no category links), you can simply set the fields parameter to names which then gives you a list of category names:

  function createGridCategories() {
      $categories = get_categories( array(
          'fields'     => 'names',
          'hide_empty' => 0,
          // other args here
      ) );
  
      return implode( ', ', $categories );
  }
  

• Or you can manually loop through the terms and just build the markup/HTML to your own liking:

  function createGridCategories() {
      $categories = get_categories( array(
          'hide_empty' => 0,
          // other args here
      ) );
  
      $list="";
  
      foreach ( $categories as $term ) {
          $url = get_category_link( $term );
          $list .= '<li><a href="' . esc_url( $url ) . '">' . esc_html( $term->name ) . '</a></li>';
      }
  
      return "<ul>$list</ul>";
  }
  

• Or alternatively (for a list/UL like the above), you can use wp_list_categories():

  function createGridCategories() {
      $list = wp_list_categories( array(
          'taxonomy'   => 'category',
          'hide_empty' => 0,
          'echo'       => 0,
          'title_li'   => '',
          // other args here
      ) );
  
      return "<ul>$list</ul>";
  }