I’m not sure I fully grasp what you want, but Restic is excellent. I use a cronjob to back up on a schedule. It’s command line only. I think there’s a tool to make it a GUI but I haven’t tried it. They have a Docker image available but it’s weird, you have to pass commands to it, it runs, then shuts down when it’s done. I love Docker but that didn’t quite work for me.
I use Backblaze B2 for storage, but any S3 will do. Restic supports all sorts of storage targets.
Credentials and things go in an .env file, or you can put everything into the command line every time.
When it’s time to restore things, you can fricken mount the whole backup you want and browse the files, copy and paste what you need, etc. That part is really cool to me.
Backblaze is $5 or $6 USD per TB per month, so 500GB will be about $36USD a year.
I’ve never had to restore a backup (yet), but to me this is the best feature of Restic.
I used Duplicati for a while (I think it was Duplicati, not Duplicacy) and although the backups seemed to work, I kept reading about people having trouble during the restore process.
Restic is a slight chore to get set up with the environmental variables, figuring out which directories to “–ignore”, etc… but man once it’s set up it’s just great.