@mchadley002 @BobTB12 Thanks for the info! I concur, it boots now! (XCP 8.2 and 8.3)
Two important hints: First ENABLE Viridian for the VM. It does not want to boot without it. Second BOOT with UEFI, BIOS does work but disk IO sucks.
I used the ISO boot image: OI-hipster-minimal-20240426.iso