In terms of builds and dependency management, Docker and nix actually work pretty similarly under the covers:
Both are mostly running well-controlled shell commands and hashing their outputs, while tightly controlling what's visible to what processes in terms of the filesystem. The difference is that nix is just enough better at it that it's practical to rebase the whole ecosystem on top of it (what you refer to as a "toolchain") whereas Docker is slightly too limited to do this.
Both are mostly running well-controlled shell commands and hashing their outputs, while tightly controlling what's visible to what processes in terms of the filesystem. The difference is that nix is just enough better at it that it's practical to rebase the whole ecosystem on top of it (what you refer to as a "toolchain") whereas Docker is slightly too limited to do this.