I’m no sysadmin or IT prof. myself, but here’s my take.
With Nix, you can build out an entire Linux operating system from the ground up with a few files. You can specify the exact versions of software and even dependencies of software so that every single installation of your OS is going to be identical. You can upgrade specific software and roll it back if it has problems. Dependencies are managed through Nix in a way that allows them to be shared where necessary (saving space) but diverging when necessary to prevent dependency hell.
The best part, imo, is that all software is from source. You don’t have to rely on package maintainers at RHEL or Debian to keep apps up to date and working - Your system will download binary blobs from the cache server or build apps from source when theyre not available. You get to have bleeding-edge apps (if you want them) without the pain of waiting 6+ months for them to come in from your distro updates.
It’s quite immature when it comes to tools that make it easier to pick up and learn, so there’s drawbacks in that regard since many IT pros will stick to tools that enterprise systems offer that make managing their infra MUCH easier.
However, Nix is imo the future of non-flatpak applications because it’s simply smarter, faster, and more declarative than RPM, Deb, Apk could ever be.