It allows me to copy select datasets inside the pool.
So I can choose rpool/USERDATA/so-n-so_123xu4 for user so-n-so. I can also choose copy copy some or all of the rpool/ROOT/ubuntu_abcdef, and it’s nested datasets.
I settle for backing up users and rpool/ROOT/ubuntu_abcdef, ignoring the stuff in var datasets. This gets me my users home, roots home, /opt. Tis all I need. I have snapshots and mirrored m2 ssd’s for handling most other problems (which I’ve not yet had).
The only bugger is /boot (on bpool). Kernel updates grown in there and fill it up, even if you remove them via apt… because snapshots. So I have to be careful to clean it’s snapshots.