I recently had to do this exact thing.
Temporarily move your local files to a non-OneDrive location, allow OneDrive to sync the empty folder to the cloud
Use Settings -> Backup -> Manage Backup to disable the top-level folder containing the now-empty directory
Use Settings -> Account -> Choose folders to disable sync of the now-empty directory
Just some general statements to a very broad question.
There are many encryption schemes, some OS-dependent, some relying on hardware, such as TPM, some performed by software such as VeraCrypt. You might research encryption standards, and decide what level of security is needed and what competencies are required for its implementation.
That said, some notes ...
(This is a copy from my answer over at Software Recommendations)
I've been doing initial tests with pCloud for this use case. I store my Lightroom catalog on an external HD that I want to backup to the cloud using their lifetime 2TB plan.
pCloud recently added backup functionality in addition to the existing sync. It's not clear to me what exactly the ...
Exclude files and extensions from syncing to OneDrive – via Group Policies,
by a Microsoft employee on May 5, 2021, describes this undocumented method,
which is quite recent in Windows.
The OneDrive sync app must be restarted after this setting is enabled
for it to take effect.
Step 1 : Add new policies to the Local GPO store
Position to folder %...
Currently, we can prevent image files being syncing to OneDrive, but we could not could not exclude specific folders to be synced to OneDrive.
Here is a similar thread "Registry exclude folder for OneDrive", on thread "Reassess the possibility to ignore or exclude selected OneDrive folders and files from the sync process." on UserVoice ...