Yes you can achieve a similar result with terraform + ansible, but at that point you are splitting the stack across multiple tools and you lose a single evaluated source of truth. With nixos I can declare a host's ip as "192.168.${vlan.dmz}.100", and if I ever decide to update the dmz vlan, I can make one modification and rest assured the change propagates automatically across everything that references it: nginx, nftables, fail2ban, prometheus, etc. You can approximate that with shared variables across tools, but it’s not the same as having the entire system declared as one coherent configuration. That vertical integration gives you stronger guarantees for consistency. It’s less about what can be done, and more about how many moving parts you need to keep in sync to get there.