extraUsers have been renamed to users. See related commits.

This will still work on 20.03 but will show a warning as name = "root"; is deprecated, and luksroot should be used instead (see boot.initrd.luks.devices NixOS option) .

boot.initd.luks.devices = {
  luksroot = {
    device = "/nev/sda2";
    preLVM = true;
  };
};

Got a warning here but it seems to be safe to ignore.

WARNING: Locking directory /run/cryptsetup is missing!

This didn't work out of the box, therefore worth looking at the Arch linux wpa_supplicant docs.

wpa_cli also wouldn't work, and needed to make sure that I had the right SSID so this link is also helpful to list available wifi networks.

On 20.03 install drops users to a non-privileged terminal so sudo su has to be entered to become root. (Otherwise the first steps in "Networking" will fail immediately.)

Saving this here for posterity: https://stackoverflow.com/questions/55191125/cant-seem-to-get-sudo-working-under-nixos