<!-- BEGIN COPY / PASTE -->
    // Register the block in a PHP file (e.g., my-custom-block.php)
    function my_custom_block_register() {
      register_block_type('my-plugin/my-custom-block', array(
        'render_callback' => 'my_custom_block_render',
      ));
    }
    add_action('init', 'my_custom_block_register');

    // Define the render callback function
    function my_custom_block_render($attributes) {
      $dynamic_content = get_some_dynamic_data(); // Fetch dynamic data
      return '<div class="my-custom-block">' . esc_html($dynamic_content) . '</div>';
    }
    <!-- END COPY / PASTE -->