% ./macos-virtualbox-vm/prepare-iso.sh
Mount the installer image
--------------------------------------------------------------------------
$ hdiutil attach /Applications/Install macOS Big Sur.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app
hdiutil: attach failed - No such file or directory
This is not the same cause as https://github.com/geerlingguy/macos-virtualbox-vm/issues/64