Exactly the product I had in mind. I think you can get customers by selling the box and also by providing a subscription model to backup/replicate the user data

Exactly the product I had in mind. I think you can get customers by selling the box and also by providing a subscription model to backup/replicate the user data. Ideally this box should use a well documented and open API and code so you can sync it with other "vaults" providers or even with other boxes. I would pay a lot for a service like this. Edit: typo.