etc_nix_nix.conf

# WARNING: this file is generated from the nix.* options in
# your NixOS configuration, typically
# /etc/nixos/configuration.nix.  Do not edit it!
build-users-group = nixbld
max-jobs = 4
cores = 0
sandbox = true
extra-sandbox-paths = /run/binfmt /nix/store/q3rh9bi26i2gzhvcsik88skk2gi76aad-qemu-user-arm-3.1.0 /nix/store/p1grzgs2wxwiddyqkn3dj3zsxyv3hzdw-qemu-user-aarch64-3.1.0 
substituters = https://cache.nixos.org/
trusted-substituters = 
trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
auto-optimise-store = false
require-sigs = true

trusted-users = root
allowed-users = *

extra-platforms = armv6l-linux armv7l-linux aarch64-linux i686-linux

morph build morph.nix

Selected 1/1 hosts (name filter:-0, limits:-0):
          0: rpi1 (secrets: 0, health checks: 0)

error: linux_rpi not supported on 'x86_64-linux'
(use '--show-trace' to show detailed location information)
Error while running `nix build ...`: See above.

morph.nix

let
  # Pin the deployment package-set to a specific version of nixpkgs
  pkgs = import (builtins.fetchTarball {
    url = "https://github.com/NixOS/nixpkgs-channels/archive/63fa75e34c12a296f2468e533407bca7c726b034.tar.gz";
    sha256 = "0vkax58nfc19r165ax5hhmzvv9afrbsj2yx2s4xvlxhjdfcrcris";
  }) {};
in
{
  network =  {
    inherit pkgs;
    description = "simple hosts";
  };

  rpi1 = import ./rpi1-configuration.nix;
}

rpi1-configuration.nix

{ config, pkgs, ... }:

{
  imports = [ <nixpkgs/nixos/modules/installer/cd-dvd/sd-image-raspberrypi.nix> ];

  services.openssh.enable = true;
  nixpkgs.localSystem.system = "armv6l-linux";

  # environment.systemPackages = with pkgs;
  # [ emacs26-nox
  #   mpv
  #   (callPackage /media/black/projects/PersonalInfrastructure/dht11reader { })
  # ];

  users.users.root.openssh.authorizedKeys.keys = [
    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIN4GenAY/YLGuf1WoMXyyVa3S9i4JLQ0AG+pt7nvcLlQ exarkun@baryon"
  ];
}