a la Boot Camp??? or similar?
Reasons being:
1) I want to be able to native boot Catalina for Metal graphics
2) I don't want to have to reboot into the Catalina machine just to read email (my office-like stuff is on the Catalina machine).
so in short, I don't want a vmdk-based machine. I would like a VM that runs over the existing APFS volume in which Catalina is already installed.