FileStorage

Would anyone know the correct settings for config.storage.active when pointing to FileStorage?

According to the Active configuration settings section of settings.php:

"/**
* Active configuration settings.
*
* By default, the active configuration is stored in the database in the
* {config} table. To use a different storage mechanism for the active
* configuration, do the following prior to installing:
* - Override the 'bootstrap_config_storage' setting here. It must be set to a
* callable that returns an object that implements
* \Drupal\Core\Config\StorageInterface.