Downloading image for Proxmox
Section titled “Downloading image for Proxmox”https://nixos.wiki/wiki/Proxmox_Virtual_Environment#LXC
”Go to https://hydra.nixos.org/project/nixos, choose a release (small ones don’t have the tarball we need), and open its Jobs tab. On that page, search for nixos.containerTarball, open the link corresponding to your architecture (probably x86_64). Choose the latest success and click on the number. That is the ID of the result. Under Build products, download the system-tarball, which will be named nixos-system-x86_64-linux.tar.xz.”