OK, now on the Fusion drive iMac (HFS+; no APFS). There are no local snapshots: either they're not taken because it's a desktop Mac or because it's not supported by non APFS systems. I suspect the former.
The only time I see snapshots is when cloning the drive to an external HD using SuperDuper! app. The first stage of a SD! backup is the creation & saving of a snapshot.
When booted into ⌘R mode, no local snapshots appear.