Does it make sense to snapshot the entire root dir or just the home directory? Asking about desktop PC.

For Solaris 11 and for Illumos based distros, snapshotting the entire root is normal. That way, with an OS update and application update, the logs are associated with that particular root file system. You can always look into earlier snapshots to learn of what the logs contained for that earlier root file system.

With Boot Environments (I don't know if Linux based Distros let one do this) on Solaris and Illumos, we have multiple active root file systems to switch between and can mark snapshots for each of them.

Certainly, for Belenix (KDE based opensolaris distro), we snapshotted the entire root file system.

bieaz: https://openzfs.github.io/openzfs-docs/Getting%20Started/Arc... zbm: https://github.com/zbm-dev/zfsbootmenu zsys: https://github.com/ubuntu/zsys