Yeah, but no dark magic involved.

• build image
• copy to proxmox ISO store
• import, resize disk
• start, wait to come online
• read ssh pubkey, save it
• rekey secrets
• rebuild VM

The only “magic” parts are two nix modules for handling proper networking and hardware setup, and exposing required attributes to the script.

Works really well, zero manual config (beyond the services you want to run…) required on nix or proxmox side.