I’ve used veracrypt for years, starting back on Windows and I still use it since I moved to Linux. I don’t use all of the features for it but what I have are encrypted volumes that exist on hard disks as a single file, which when opened with veracrypt, show themselves as a new disk in the system.

There’s probably better ways to encrypt data on onedrive, but you could probably create one of those encrypted volumes to store on onedrive.