D8 Taxonomy tree to nested HTML list

anywhere.php

<?php

$vocabulary_name = 'my_machine_name';
$root_tid = 0;

$vocabulary = $this->vocabularyStorage->load($vocabulary_name);
$terms = $this->termStorage->loadTree($vocabulary->id(), $root_tid);
$tree = [$root_tid => []];
foreach ($terms as $term) {
  $tree[$term->tid] = [
    'title' => ['#markup' => $term->name],
  ];
  if (empty($tree[$term->parents[0]]['children'])) {
    $tree[$term->parents[0]]['children'] = [
      '#theme' => 'item_list',
      '#items' => [],
    ];
  }
  $tree[$term->parents[0]]['children']['#items'][] = &$tree[$term->tid];
}

$build = $tree[$root_tid]['children'];