I think the last missing piece is getting reproducible builds which I think you can get from buildpacks [0], NixOS [1], or Bazel [2] running in your CodeBuild.
I was thinking someone could probably build a manyrepo solution similar to Brazil on top of an idea like this. I don’t see many tools like Bazel built for manyrepos.
There’s no equivalent OSS implementation of a multi language lock file like Brazil’s. You have to build your own or go with a monorepo tool like bazel. Amazonians take reproducibility for granted because of Brazil.
I’d be happy if I’m wrong about this but I don’t think you can get a reproducible Node.JS build or python build from NixOS out the box. You need to build something on top of it.
[0]: https://buildpacks.io/docs/features/reproducibility/
[1]: https://nixos.org/
[2]: https://testdriven.io/blog/bazel-builds/