Branch menu as submenu with excluded sub(-sub)pages, displayed on one level

Sorry to harp on this.

What I did before was a tree display, but actually I try to get just the branch.
This Kirby blog article helped to solve at least the second level part:
https://getkirby.com/blog/fun-with-menus

What I could do is to call two loops: one for the first level (in this case “artist …” – in the Kirby hierarchy a sublevel) and one for the second level (in the Kirby hierarchy a sub-sublevel).

The loop (for “artist …”) taken from the blog example is this:

<?php

$items = false;

// get the open item on the first level
if($root = $pages->findOpen()) {

  // get visible children for the root item
  $items = $root->children()->visible();
}

// only show the menu if items are available
if($items && $items->count() > 0):

?>
<nav>
  <ul>
    <?php foreach($items as $item): ?>
    <li><a<?php ecco($item->isOpen(), ' class="active"') ?> href="<?php echo $item->url() ?>"><?php echo html($item->title()) ?></a></li>
    <?php endforeach ?>
  </ul>
</nav>
<?php endif ?>

What I obtain is that all the artists are listed. But I only want to see the current artist, both on the artist level and the second level. Is there any way to solve this?