{hardware, ...}: {
  imports = [hardware.hetzner-x86];
  settings = {
    sshPublicKey = "ssh-ed25519 ...";
  };
}
{hardware, ...}: {
  imports = [hardware.hetzner-x86];
  settings = {
    sshPublicKey = "ssh-ed25519 ...";
  };
}

You can access the hardware special argument in the Nix modules of your machines. This argument contains Nix modules that can be imported into your machine configuration. Each module defines a set of opinionated defaults, such as the file system layout, the bootloader, the kernel, the init system, etc.

When possible, the hardware modules also define a disko partitioning scheme, which can be used when installing the system using the install command which is a wrapper around nixos-anywhere.

The available hardware modules differ depending on the host system, whether the machine is a NixOS machine.

You can find the list of the available modules in the hardware modules reference.