将Neos Fusion渲染的标记片段添加到Elasticsearch索引中，可以使用Neos的Elasticsearch包来实现。以下是一个简单的示例：

use Neos\Eel\FlowQuery\FlowQuery;
use Neos\Fusion\Core\Cache\ContentCache;
use Neos\Flow\Annotations as Flow;

/**
 * @Flow\Scope("singleton")
 */
class ElasticsearchIndexer
{
    /**
     * @Flow\Inject
     * @var Elasticsearch
     */
    protected $elasticsearch;

    /**
     * @Flow\Inject
     * @var ContentCache
     */
    protected $contentCache;

    /**
     * @param NodeInterface $node
     * @throws Exception
     */
    public function index(NodeInterface $node): void
    {
        $contentCacheIdentifier = $node->getNodeData()->getContentCacheIdentifier();

        $cachedRenderedMarkup = $this->contentCache->get($contentCacheIdentifier);

        if ($cachedRenderedMarkup !== null) {
            $documentId = $node->getIdentifier();

            $document = [
                'markup' => $cachedRenderedMarkup
            ];

            $this->elasticsearch->index([
                'index' => 'my_index',
                'type' => 'my_type',
                'id' => $documentId,
                'body' => $document
            ]);
        }
        else {
            // ...
        }
    }
}

此方法可以将节点渲染为标记片段，将其添加到Elasticsearch索引，并在查询时使用。