Oops should have done my own research first (doh me)
As per Apple Discussions: Mojave supports APFS on Fusion Drives
Interesting though that Time Machine and APFS do not play nice.
Types of disks you can use with Time Machine on Mac
Here is a quote from that link: "Important: You can back up from an HFS+ or APFS-formatted disk to an HFS+ disk; however, Time Machine can’t back up to an APFS-formatted disk. If you select a back up disk formatted as APFS, Time Machine offers to reformat it as HFS+."


