Vorta only supports SSH and local backup repositories while pika allows SFTP through some kind of compatibility layer with gvfs.

That's kinda wild given SFTP is just SSH.

If you're flinging files across the network, rsync is usually a really good option. It'll typically be run over SSH/SFTP and is capable of resuming if interrupted, verifying the copied files match the original, etc. and rsync can be super fast compared straight SFTP in some cases. In a pinch you can always cobble together a pretty robust backup script purely based off rsync