How Do I Create A VirtualBox VM From An Existing macOS Mojave APFS Volume? I saw a related post but the instructions were specific to VMware Fusion, which I am not using.

With Carbon Copy Cloner, I created a bootable backup of the existing macOS Mojave installation that I want to turn into a VM. 

Do I need to include The Container when I convert that clone into an iso or cdr?

Yesterday, I made a macOS Mojave VM directly from the macOS Mojave Installer using the instructions and tools here: AlexanderWillner/runMacOSinVirtualBox

The post about doing this with VMware suggests adding the iso/cdr clone of the boot drive you want to virtualize to an existing Mojave VM. Would this work in VirtualBox, given that VirtualBox still doesn't technically support booting from APFS drives?

I'm not particularly familiar with VirtualBox and I don't want to purchase VMware or Parallels. What will be the simplest way to convert my existing macOS Mojave APFS installation into a VirtualBox VM?
I suggest you use the free Parallels Lite found in the app store.  You have to pay to run Windows!  Running macOS is free.
https://itunes.apple.com/us/app/parallels-desktop-lite/id1085114709?mt=12

Virtual box doesn't support macOS that well.