After multiple trial and error attempts, we finally mastered APFS and are ready to share the knowledge on creating APFS bootable backup with macOS command line. Having such copy on an external drive is rather useful in case something disastrous happens to your local disk, you will have an exact copy of the disk that can be connected externally to your Mac and boot it up. Clone copy of your disk will protect you against any physical or software damage to your computer and system disk, by preserving all the essential files and data.
All of the commands below should be used in Terminal app on macOS 10.13 (High Sierra) and macOS 10.14 (Mojave). Highlighted in bold parts should be replaced with your own respective volume name, disk ID, etc.
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