@planedrop Thought you might be interested to hear my results... The Vendor A) refuses to talk to me since I'm an MSP and not a direct employee of my client... Stupid, but I sent questions to my clients to give them...
They have straight-up refused to discuss trying anything outside of Hyper-V and completely acted stupid when I mentioned something about moving the VHD that their software creates in Hyper-V and put it in our hypervisor directly... Said that's unsupported and we will not assist you.
Still trying to figure out how to get around this... I had Hyper-V running on a Proxmox VM but the software seems to stall out and never finish installing. I'm trying XCP-NG 8.2 but based on all the conversations here, I'm assuming Hyper-V will refuse to run.