How easy do you estimate to be adding new storage backends to Kratos? I would like to use it as a way to do user management, but I need to be able to save data

How easy do you estimate to be adding new storage backends to Kratos? I would like to use it as a way to do user management, but I need to be able to save data about users to custom storage backends (built on top of boltdb, badger, etc)