Drupal 9: Redirect view with only one result to the result directly

For a certain view, if it returns only one result, you wish to redirect the users to the single result URL?

This is possible by choosing the right hook "hook_views_post_render()", here you go (example implementation):

/**
 * Implements hook_views_post_render().
 */
function MY_MODULE_views_post_render(\Drupal\views\ViewExecutable $view, &$output, \Drupal\views\Plugin\views\cache\CachePluginBase $cache) {
  // Redirect to the views result, if there's only one.
  // Only redirect on view id "products_faceted_search" and do NOT redirect if an exposed filter is set.:
  if (in_array($view->id(), ['products_faceted_search']) && $view->total_rows == 1 && count($view->getExposedInput()) == 0) {
    // We have to kill the page cache here otherwise this hook will not be called again on the second request.
    \Drupal::service('page_cache_kill_switch')->trigger();
    // We also have to clear the views cache to make this work at 2nd call:
    $cache->cacheFlush();
    if (!empty($view->result[0]->_entity)) {
      $entity = $view->result[0]->_entity;
      $language = \Drupal::languageManager()->getCurrentLanguage(LanguageInterface::TYPE_CONTENT);
      $entity = $entity->getTranslation($language->getId());
      $url = $entity->toUrl();
      // Display a notice for administrators. Do not redirect.
      if (count(array_intersect(['administrator','manager'], \Drupal::currentUser()->getRoles()))>0) {
        \Drupal::messenger()
          ->addMessage(new TranslatableMarkup('This page is set to redirect to another URL (@url), but you have permission to see this page and will not be automatically redirected (via MY_MODULE_views_post_render).', ['@url' => $url->toString()]), 'status');
      }
      else {
        // Do not redirect cron
        // From https://git.drupalcode.org/project/field_redirection/commit/42b8891
        // Don't execute if running via the CLI, e.g. Drush.
        // Don't do anything if the current page is running the normal cron script;
        // this also supports Elysia Cron.
        $current_url = Url::fromRoute('<current>');
        $current_path = $current_url->toString();
        if (mb_strpos($current_path, '/cron') === 0) {
          return;
        } elseif ($current_path === '/admin/reports/status/run-cron') {
          return;
        } elseif (defined('MAINTENANCE_MODE')) {
          return;
        } else {
          // Redirect regular users.
          $response = new \Symfony\Component\HttpFoundation\RedirectResponse($url->toString());
          $request = \Drupal::request();
          // Save the session so things like messages get saved.
          $request->getSession()->save();
          $response->prepare($request);
          // Make sure to trigger kernel events.
          \Drupal::service('kernel')->terminate($request, $response);
          $response->send();
        }
      }
    } else {
      throw new Exception('No result returned');
    }
  }
}

Note: This doesn't yet seem to work with views caching enabled, help appreciated :)

Even better would be to have this as module with a view setting or something like that, but that's a different story ... :)