node_duplicate.module

<?php
// This operation relies on Drupal's destination handling
// in admin views to return the user to the content listing.
declare(strict_types=1);

use Drupal\Core\Entity\EntityInterface;

/**
 * Implements hook_entity_operation_alter().
 */
function node_duplicate_entity_operation_alter(array &$operations, EntityInterface $entity): void {
  if ($entity->getEntityTypeId() !== 'node') {
    return;
  }

  $account = \Drupal::currentUser();

  $create_access = \Drupal::entityTypeManager()
                          ->getAccessControlHandler('node')
                          ->createAccess($entity->bundle(), $account, [], TRUE);

  if (!$create_access->isAllowed()) {
    return;
  }

  if (!$entity->access('view', $account)) {
    return;
  }

  $operations['duplicate'] = [
    'title' => t('Duplicate'),
    'weight' => 25,
    'url' => \Drupal\Core\Url::fromRoute('node_duplicate.duplicate', [
      'node' => $entity->id(),
    ]),
  ];
}