APFS Encryption Status
macOS offers us a super simple way to fully encrypt an APFS formatted external drive: Right-click on the volume in the Finder and choose the option "Encrypt". Carbon Copy Cloner (CCC) also recommends this in its KB article Enabling encryption on a volume that will not contain an installation of macOS.
But macOS is a bit too transparent on that task. It simply starts encrypting the volume without any feedback or progress bar (WTF?). Even Disk Utility just shows the volume as
APFS (Encrypted) - as it would have already completed full volume encryption.