Nix lets you build docker images. Those images won’t have Nix program installed, but they will have the exact same binaries as specified in the shell.nix (for reproducibility). You could run production with Nix instead of Docker but it would be less convenient and require additional setup on the servers.
PS. When saying Docker, I mean any OCI-compatible software. Containers are an open standard
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TIL, Nix is indeed 20 years old, damn.