When I setup my backup strategy, the Hetzner storage boxes showed the best price per TB, and allow ssh / SCP and webdav access.
I run a virtualized TrueNAS Scale with a passed through HBA and about 6 drives in raid-z2 mode. I setup TrueNAS to do regular snapshots - hourly, daily, monthly and I use the built in encrypted backup options to backup my most important data every night (personal videos and pictures, VM backups, documents, docker volumes).
This works like a charm and it seems to be also quite stable. If the system ever dies, I can always simply mount the encrypted backup folder on my laptop using rclone, and then manage my files directly using mc.
I use Hetzner Storage Box for my backup needs - TrueNAS handles this for me on a regular interval and encrypts them before upload (yay rclone!). I needed a bit more storage than you, to the tune of 5TB, and for this much data they were the cheapest (12eur / 15usd per month iirc).
Consider slightly more storage if you need snapshots. For my storage box i enabled them, and now have a history of last 4 monthly backups.
If you use rclone, you can mount the remote backup as a fuse filesystem and browse your backup like it would be a local file - extract what you need only. Any livecd / USB with rclone can help you rescue your data in case of disaster.