I’d love to see a key only service just as you describe. That would be really cool.
Discussion
Otherwise, if you're not careful with your IP address they have your information regardless of your KYC.
But yeah that service exists tbh...
You just do it yourself with the same service these MFers use.
https://www.ironmountain.com/services/iron-cloud-data-management
I would also go for their physical backup service.
Nice tip!