1. For Raspis it's the easiest if you prepare the SD card/disk on another system. For a PC you can just boot the installation ISO directly.
1. For both devices you can format the disk/card with the following script `sudo ./scripts/format-disk.py`. It will walk you through the formatting process and for a Raspi4 it will prepare it for UEFI setup.
1. Next install the system with `sudo nixos-install --no-root-passwd --root /mnt/nixos --impure --flake .#SYSTEMNAME`