[matrss]

> Opensuse with snapshots and some repo magic, can do 99% of functionality, [...]

I doubt that.

Does Opensuse have an integrated declarative configuration management system?

How would I apply a patch to a program on Opensuse and build that program the same way as the distro-provided package was (i.e. into a rpm that I can then install)? What about changing compiler flags?

How do I get an isolated development environment going with Opensuse, i.e. one that does not pollute the list of system-wide installed packages?

How can I check if a package provided in the Opensuse repositories was not tampered with, i.e. the provided build instructions actually produce this package? Are there even build instructions for the rpm's provided?

There is a lot more that nix and NixOS can do, this is just part of what came to mind on what I would assume is mostly impossible on "traditional" distros.