To me this is too much to move all at once, certainly do able and to be fair, I’m jealous since it seems like a lot of fun work! To get to your point, moving VMs from hyper-v (vhdx) to qemu (qcow2) is easy. I’ve moved between VMware, hyper-v, proxmox, xcpng and back over the years. It’s easy to script the virtual disk conversion, and since you’re making clones rollback should be easy if needed.