That would be a cinch with a Mac one decade ago, or 20 years or 30 years ago, or probably even back in 1985.
But these days, when it comes to external bootable drives, Apple vacillates between neglect and hostility.
I've lost track of the current status of bootable backups on the Mac. Based on the following blog, it seems there's some new insult to the process once or twice a year: https://eclecticlight.co
