Mac not detecting MDS bootdrive

Followed the setup video to the T… tried multiple boot drives yet the Mac won’t detect the mds bootdrive

I’ve also set up an admin account to deactivate the bootdrive security yet nothing is detected when choosing a drive to boot from

Usually you boot from recovery and then run the workflow running from the external drive. You can make the external drive bootable, but that is only for older macs. Newer Macs require external booting to be enabled with Secure Startup Utility in recovery.