What data repair and recovery options exist for a missing APFS Volume? I am using an OWC Envoy Pro enclosure with an Apple Samsung SSD out of a 2015 MacBook Air. It's plugged into a 2017 iMac 27". 

The External SSD) randomly gets ejected and as a result of this random ejecting I have now lost the volume. Only the base SSD drive/name and container are there. 

Is there anyway to recover the data or the entire APFS volume?
How to Recover Lost Data from APFS Volume on Mac

https://recoverit.wondershare.com/harddrive-recovery/how-to-recover-lost-data-from-apfs-volume.html

It will cost you $40

or this one https://www.ibeesoft.com/data-recovery-software/mac-data-recovery.html

You can always try to do it your self with Disk Utility.

https://blog.macsales.com/44912-new-capabilities-limitations-how-disk-utilitys-restore-feature-changed-in-high-sierra