I have found those options for setting up iscsi, but since I am new to nixos (started yesterday) I don't have any idea how to configure the configuration.nix file to setup iscsi.
I already installed open-iscsi but it doesn't work on nixos it seems
If you don’t have any idea how to configure a configuration.nix, you need to start there. In my opinion, NixOS is not like any other distro and if you try to treat it like a normal distro, you will have a bad time.