First, a clarification: backups should always be in a consistent state and therfore only be used to either restore individual files or the entire backup. No sync clients should touch them and you should not work with the backed up files directly.
Now to the practical things:
10GB of data, of which most is at rest, is not a big deal nowadays. That means the performance of the backend doesn’t play a big role and you could basically use any cloud storage provider you want, as long the backup software you use, supports it. So you could use the Nextcloud you already have without any problems.
The key points are:
- use a backup software for doing backups instead of a sync client
- the data should be automatically encrypted before uploading for privacy and security reasons.
- the data on the cloud storage should not be touched by anything else except the backup software
With that in mind, you could theoretically even use the rest of the Nextcloud with sync and all other functions normally, as long as the backup data stays in it’s own seperate folder and doesn’t get touched by the sync client.
About the software:
I don’t have that much experience with backup software that runs directly on Windows clients or generally on endpoints, because all my files are on my home NAS / Server and I do the backups from there. But I would recommend to have a look at Duplicati. It runs on Windows, Mac and Linux. It has a WebGUI to manage the backups and supports all possible and impossible storage backends and cloud providers, including WebDAV.
If you are looking for a more classic all-in-one endpoint backup solution, this might be worth a look at…
…but I don’t know if it encrypts the data before uploading it, if you use their software, which I think you have to with this solution.
If you don’t want to use their client software, you could also use the B2 Storage offer from Backblaze in combination with Duplicati. Backblaze B2 is actualy what I use for my cloud backups.
In addition to the cloud backup, I would also consider doing local backups if you don’t already do so. This can be as simple as using a USB disk or a small NAS server… Then you would have a full 3-2-1 backup solution
The 3-2-1 rule can aid in the backup process. It states that there should be at least 3 copies of the data, stored on 2 different types of storage media, and one copy should be kept offsite, in a remote location
I hope this helps you for now… If you have more questions feel free to ask