virtualbox.org

Using VB 6.1 running in Fedora 31 I have configured a guest OS to properly start at boot with VBoxManage startvm Win --type headless This works just fine.

From the VirtualBox Manager GUI there is a "Show" button for a running guest, which again, works as expected. My question is, would there be a command line option to perform this same task.

I have read through much documentation plus google, nothing seems relevent

Yes, 'VBoxManage startvm Win --type separate', same as if you're starting it detachable instead of headless.

The only command missing in the whole scheme is the one that would hide the window. A host-key combo can be set for that, to run the guest Machine menu, Detach GUI.