I really like ZFS snapshots with offsite pull-mode sync using
Jim Salter's sanoid/syncoid [1]. ZFS is the base for all OS/filesystems on top of it. If you have a good system for organizing ZFS datasets, and separating ephemeral from persistent data (e.g. [2]), then this is 90% of the backup requirements already fullfilled.
[1]: https://github.com/jimsalterjrs/sanoid
[2]: https://du.nkel.dev/blog/2026-05-16_rootless_docker_virtiofs_proxmox/