Hi All,
thanx for the Help.
It had nothing to do with the boot order.... the HDD was not even recognised: "No Bootable device found"...
But: I fixed it now.
The trick was... i hade to install a different OS (Deb12) befor on the newly created virt.HDD... after that i booted from the Appliance iso and installes Grommunio over the now previosly installed OS.
After that GRUB was properly initialized on the virt.HDD so that the VM is now booting. The HDD gets recognized, and the Appliance is booting.
I have absolutely no idea, why just creating the VM an installing the appliance did not properly initialise GRUB in the first place. Something wrong in the RAW Immage in the Appliance.iso?
But it was reproducable for me....
Anny, how, now next steps in Testing :-)
Thanx again for Help an Suggestiones.