Parse entity_embed module markup
The body contains tokens set when you press an embed button in ckeditor.

This raw body content is processed by this filter:

http://cgit.drupalcode.org/entity_embed/tree/src/Plugin/Filter/EntityEmbedFilter.php

 public function process($text, $langcode) {
    $result = new FilterProcessResult($text);

    if (strpos($text, 'data-entity-type') !== FALSE &amp;&amp; (strpos($text, 'data-entity-embed-display') !== FALSE || strpos($text, 'data-view-mode') !== FALSE)) {
      $dom = Html::load($text);
      $xpath = new \DOMXPath($dom);

      foreach ($xpath-&gt;query('//drupal-entity[@data-entity-type and (@data-entity-uuid or @data-entity-id) and (@data-entity-embed-display or @data-view-mode)]') as $node) {
        /** @var \DOMElement $node */
....


You would have to build a view mode in ui with only the body field or apply the filter in code.