Your scanning credentials are stored in your database using a salted hash, encrypted using file encryption using the local encryption file unique to your Lansweeper installation. It's unfortunately not possible or very difficult to replicate this using an upgrade script. The same would be true for an API, though we currently only offer an API for the helpdesk module.
Integration with 3rd party password manager has been requested before recently and is already on our customer wishlist. I've added your feedback to our internal feature tracking system in this context and have moved this topic to the wishlist section. At this moment in time this feature is not yet in active development, so I'm not able to guarantee that it will be added and can't provide an estimated release date.
If you have any additional feedback to add in the context of a password management feature feel free to add it.