<!-- BEGIN COPY / PASTE -->
    // JavaScript: Register the block
    wp.blocks.registerBlockType('myplugin/dynamic-block', {
      title: 'Dynamic Block',
      category: 'widgets',
      edit: function() {
        return wp.element.createElement('p', {}, 'Dynamic Content Placeholder');
      },
      save: function() {
        return null; // Server-side rendering
      }
    });

    // PHP: Render the block content
    function render_dynamic_block() {
      $content = '<p>' . get_dynamic_content() . '</p>';
      return $content;
    }
    register_block_type('myplugin/dynamic-block', array(
      'render_callback' => 'render_dynamic_block',
    ));

    function get_dynamic_content() {
      // Fetch and return dynamic content here
      return 'This is dynamic content!';
    }
    <!-- END COPY / PASTE -->