The execution environment for a product is certainly reproducible with Docker, assuming you actually make your base image Dockerfile work in a reproducible environment as well.
You can also use Dockerfiles as units of deployment for individual software projects, which offers that.
While it is true that NixOS offers a different vision for how to solve these problems, it does so in a way I find very destructive for actual use. It seems inferior for deploying software compared to containerization (which offers immutable and composable build artifacts), and very cumbersome to work with during software development (since the value of writing nix packages during development is cumbersome and for many language environments you have to deploy the source code in the package and compile it within the closure you expect to deploy on to make any headway).
You can also use Dockerfiles as units of deployment for individual software projects, which offers that.
While it is true that NixOS offers a different vision for how to solve these problems, it does so in a way I find very destructive for actual use. It seems inferior for deploying software compared to containerization (which offers immutable and composable build artifacts), and very cumbersome to work with during software development (since the value of writing nix packages during development is cumbersome and for many language environments you have to deploy the source code in the package and compile it within the closure you expect to deploy on to make any headway).
Ya'll can pretend https://github.com/NixOS/patchelf doesn't exist because these problems are incredibly irritating, I guess.