Override the default private file access

In the site I am developing, the private files directory is outside the document root.
I have a content type (Chapter) with a file field that stores its files in the private files directory. When a Chapter node is published, its file is accessible to users, but when the node is unpublished, its file is not accessible to users. They get an access denied page.

How can I control the access to the attached file and allow users to access the attached file when the node is unpublished, in a custom module?

With Drupal, the access to private files is determined by access to the entity to which they are attached. I would create a new media entity type, setting the file storage to be private. Then you can set up custom access rules for the entity type, using standard Drupal methodology. Users with access to that entity will be allowed to access the private file, and users without access to that entity will be denied access to the file. Then you can attach the media item to whichever node or other entity you need.

The expected normal behaviour described above does not seem to work. i Have had to :

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Session\AccountInterface;
use Drupal\node\NodeInterface;
use Drupal\user\Entity\User;
use Drupal\media\MediaInterface;

function my_module_media_access(MediaInterface $media, $op, AccountInterface $account) {

  if ($op !== 'view') {
    return AccessResult::neutral();
  }

  $user = User::load($account->id());
  if ($media->bundle() === 'media_private') {
    $acces = AccessResult::forbidden();
    if ($user->hasRole('private access people') || $user->hasRole('administrator')) {
      $acces = AccessResult::neutral();
    }
    return $acces;
  } 
  return AccessResult::neutral();
}