Over the internet for file sync. Desktop devices.

The data is integrated into the Internet archive and available e.g. via the way back machine. Not sure if you can get the whole reddit dataset.

The archive warriors are downloading Reddit for a while already. 15.6 billion items and counting. You can help too:

https://tracker.archiveteam.org/reddit/

I heard good things about Newsblur. They offer a service and an open source version for self hosting

https://github.com/samuelclay/NewsBlur

This is a great hint, thank you. I just discovered that the official restic docs recommend this method too

Thank you!

https://restic.readthedocs.io/en/latest/080_examples.html

This might be a good idea. It would only work for files that allow read access for the group, but that should be fine

Restic uses smart Delta backups, creating a tar before the restic process would defeat the purpose. The permission issue is the same, as I need to have access to the Files either way.