Show disabled layouts without workaround / hide uninstalled disabled

Issue for this code / comment:

// Already disabled layouts have already been removed here because the form is built after layout_disable_layout_alter.
    // So we have to make them available manually:
    if (!empty($settings['disabled_layouts'])) {
      \Drupal::messenger()
        ->addWarning('If already removed from code (disabled) layouts appear here, uncheck them to remove them finally. They are still listed due to a hook_layout_alter logical incompatibility.');
      // TODO - This may lead to listing already uninstalled layouts here. Find a way to only show existing layouts despite alteration.
      $layout_names = array_merge($settings['disabled_layouts'], $layout_names);
    }

We'd need a further "status" variable instead of unsetting the disabled layout from the layout_array in layout_disable_layout_alter(). Perhaps we'd need a core feature request or find a better solution to get the list without the alter() call.