Reproducibility is a spectrum. A good starting point is to snapshot the exact version of the code that produced a model. Even better, you should snapshot the full dependency graph, including transitive dependencies, of all (compiled) libraries, which Metaflow does with @conda. Together with data snapshots, this gives a pretty good foundation for reproducibility.

Depending on the libraries you use, the exact results may or may not be reproducible on other architectures. If cross-platform reproducibility is important to you, you should choose your libraries accordingly. Metaflow provides the tools for choosing the level of reproducibility that your application requires.