What we have today is that there is a multitude of dependency managers and - what's worse - all of them are _also_ build tools targeted at specific language.
Nix has a unique position because it is not language specific. Where it is lacking is missing standards and reusable libraries that would simplify common tasks.
I am comparing to Maven because I am looking for multi-platform Maven alternative. There is Bazel but its dependency management is non-existent. There is Buck2 which is great in theory but the lack of ecosystem makes it a non-starter.
Nix is the only contender in the space that offers almost everything and has a chance to become a de-facto standard of software delivery thanks to this.
What's missing though is... easy to use canned solutions similar to maven plugins.
EDIT: grammar