In my setup I combine one machine with ZFS with another running btrsfs, therefore using rsync/restic. And Apple devices uses APFS. I'd rather use ZFS solely (or in future: bcachefs) but unfortunately Apple went w/their native next-gen CoW filesystem and I don't think ZFS is available for Synology DSM. Though perhaps I should simply replace DSM with something more my liking (Debian-based, Proxmox).