OneDrive Alternative

I’m working on moving away from MS Office. Installing LibreOffice was the easy part. However, I also need an alternative for online storage.

My primary use case is off-site backups for the most critical data from my NAS (around 300 GB). Ideally, the solution would also support additional software, helping me move away from non-EU applications. I’m looking for something reliable, easy to set up, and scalable over time.

In my research, I came across Hetzner’s managed storage, which seems promising (link). Nextcloud appears to be a flexible starting point. It offers reasonable pricing and servers based in Germany.

I also considered Proton, but it seems overpriced if I only need the storage component.

Are there other options I might have not considered?

Edit: Thanks for the input everybody. I think I will try out nextcloud for a while and when this is too complicated and time consuming, I might try one of the other good solutions here.