While attempting to create a new VM I get the dreaded unable to create installation media message when creating a new VM with a Big Sur beta 10 installer. Beta 6 installer worked while Beta 9 and Beta 10 installers fail to create the installation.
We need an update from Apple or VMWare to resolve this as one of the touted features of Fusion 12 is Big Sur support.
Yes, I can confirm it doesn't work as it should in VMware Fusion 12 with creating installation media of Big Sur 11.0.1
However there's a workaround here see the answer from taylorcurtis805 in thread unable to create installation media
With those steps I was able to create a .dmg that did boot and let me install Big Sur in a VM.