"Reproducible" is a nice word, but I feel like if the granularity of the contents is "other APKs", then it's not as useful as reproducibility in tools which allow more arbitrary contents.

I know some people don't like seeing it brought up in every thread, but if you're talking about declarative, reproducible, minimal, SBOMs, non-Dockerfile building of OCI images, I think a comparison to Nix would be useful. -- Probably a tool like this is easier to use, and surely quicker; but with this you're restricted to just bunch of existing APKs.