Resurrecting an Unsaved Drupal 8 Node from the Database using Devel

resurrect.php

<?php
// NOTE: Node previews expire after 7 days. Be sure to use this method to extract the desired data before then.

// IMPORTANT: Set this to the user ID of the person who was creating/lost the node.
$user_id = 1;

// IMPORTANT: Set this to the UUID that appeared in the node preview URL.
// This value is from a URL that looked like this:
// https://my-site/node/preview/ed4eaac0-3c32-427e-860f-6ce8fc79c3b2/full
$preview_id = 'ed4eaac0-3c32-427e-860f-6ce8fc79c3b2';

$user = user_load($user_id);

$account_proxy = new \Drupal\Core\Session\AccountProxy();
$account_proxy->setAccount($user);

$temp_store = new Drupal\Core\TempStore\PrivateTempStoreFactory(
  \Drupal::service('keyvalue.expirable'), 
  \Drupal::service('lock'), 
  $account_proxy, 
  \Drupal::service('request_stack'), 
  604800
);

$preview_converter = new \Drupal\node\ParamConverter\NodePreviewConverter($temp_store);

$preview = $preview_converter->convert($preview_id, NULL, NULL, []);

$preview_array = (array)$preview;

// The values of the node form are under a key called "*values".
dpm($preview_array);