Nope thats what sharepoint365 and teams(which does include an file store in it;s channel feature) comes into play but the back end and api's are essentially the

Nope thats what sharepoint365 and teams(which does include an file store in it;s channel feature) comes into play but the back end and api's are essentially the same as for one drive. MS have done a good job of tying everything into a big entangled system where it's hard to disentangle any of the "on prem" products like windows and office offline from the cloud backend used by office365, and a lot of this is introduced gradually with standard(often security critical) updates it gets used without a lot of policy. You can backup the office365 data elsewhere(were using aws s3 buckets for office365 backups where i work) but that's not cheap nor particularly easy to do and the need to do so is often overlooked when the contract for o365 is signed.