I have to agree regarding the UX, though I would like to add that it is the language per se that is complex, but its standard lib/“nixpkgs” lib.
Also, not sure I can see where would you not recommend git? Is that a typo? It sure has a bad UX, but it is the lingua franca of version management either way, that even junior devs will have to fight to understand to become even remotely useful. And this might well be the case with nix as well.
I would not recommend git for organizations with monorepos, and not for companies that need to store large binaries (like games; git-lfs is a start but still a royal pain). Also I probably wouldn't recommend git for projects that are significantly more media than code. Depends on the team.
Git dominates open source, yes, but I wouldn't call it a lingua franca in general. Most companies I've consulted with were doing just fine with something else.
Also, not sure I can see where would you not recommend git? Is that a typo? It sure has a bad UX, but it is the lingua franca of version management either way, that even junior devs will have to fight to understand to become even remotely useful. And this might well be the case with nix as well.