This allows you to take a fully-fledged macOS installation with you wherever you go, for use on any Sierra-compatible Mac. The method described here actually creates a fully functioning macOS Sierra installation on an external USB device. Keep in mind, this is not the same as using an external device to install macOS, which lets you install macOS from an external USB device.
Ever wish you could take your Mac with you on an external drive? You can actually install macOS Sierra on an external drive, flash drive, or SD card, then use that device as your macOS system disk wherever you go.
