I am not sure I would call NixOs a rolling release distribution. It has releases every 6 month like Ubuntu, but it does not have LTS releases. And due to the relatively small community only the latest release is supported. I am doing software development on a desktop workstation, that followed all releases since the start of 2018. And overall it has been rock solid. If an update, either a new release or a config change of mine, breaks something important, I reboot with the previous setup, and I can continue to work until I have time to investigate what is going on. I've used that perhaps 5 times since 2018. But when I used it, it was absolutely critical.
NixOS is programmed in a functional programming language and aims to be fully pure and reproducible. Using it since over a year now and my entire hackspace runs on it. Can highly recommend it.
