To enable install over ssh, edit modules/iso-config/default.nix, add ssh key to nixos user.

To enable tailscale, edit modules/iso-config/tailscale-up.nix providing authkey, and optionally changing login-server if running your own headscale instance. If using this option, authkey should probably be reusable, and acls.json setup to isolate the install user / namespace.

For the installed system, set hostname and username in modules/iso-config/home/config/extra-config.nix. Optionally set hashedPassword in the user definition section.

modules/iso-config/home/config contains the flake for the installed system; edit, add modules, imports, etc as desired.

To build the iso:

nix build \.#nixosConfigurations.iso.config.system.build.isoImage -o iso

or

nix build \.#nixosConfigurations.iso-vm.config.system.build.isoImage -o iso

The vm variant is suitable for headless libvirt / qemu vms, console output will be visible on bootup.

To install, once installer boots, if prep.sh or prep-zfs.sh needs to be edited, copy out of config to edit (e.g., set disks, etc, particularly in the zfs case). Run with sudo, beware there are no prompts, will start by wiping disks. Recommend using the vm variant to get a feel for things, in which case, uncomment the vm console section in extra-config.nix to get proper tty output.