SSD #0
│─ boot 1G vfat (ESP, kernel)
│─ swap 1G 17G (16G) swapdevice
└─ root 17G 100% XFS

sudo -i
# partition disk
parted /dev/nvme0n1 -- mklabel gpt
parted /dev/nvme0n1 -- mkpart ESP fat32 1MB 1G
parted /dev/nvme0n1 -- set 1 esp on
parted /dev/nvme0n1 -- mkpart swap linux-swap 1G 17G
parted /dev/nvme0n1 -- mkpart root 17G 100%
# helper vars for easier copypaste
boot="/dev/disk/by-id/nvme-Samsung_SSD_960_EVO_250GB-part1"
swap="/dev/disk/by-id/nvme-Samsung_SSD_960_EVO_250GB-part2"
root="/dev/disk/by-id/nvme-Samsung_SSD_960_EVO_250GB-part3"
# enable swap
mkswap -L swap "$swap"
swapon "$swap"
# format root part
mkfs.xfs "$root"
mkdir /mnt
mount "$root" /mnt
# format boot part
mkfs.fat -F 32 -n boot "$boot"
mkdir /mnt/boot
mount "$boot" /mnt/boot
# gen config, if needed
nixos-generate-config --root /mnt
# if not needed, now is a great time to clone/copy over your config
nixos-install --root /mnt
# set the root password when prompted, then reboot to your new system

fileSystems."/" = {
  device = "/dev/disk/by-id/nvme-Samsung_SSD_960_EVO_250GB_S3ESNX0K366033D-part3";
  fsType = "xfs";
};

fileSystems."/boot" = {
  device = "/dev/disk/by-id/nvme-Samsung_SSD_960_EVO_250GB_S3ESNX0K366033D-part1";
  fsType = "vfat";
  options = [ "fmask=0022" "dmask=0022" "umask=0077" ];
};

swapDevices = [
  { device = "/dev/disk/by-id/nvme-Samsung_SSD_960_EVO_250GB_S3ESNX0K366033D-part2"; }
];