Comment 2 for bug 1711333

snaps nowadays ship /snap/<snap name>/current/snap/snapcraft.yaml which should have most/all build information in it already ... (upstream source, binaries that are used from the archive, patches (or at least a source to the build system used to build it to look up patches))

That said ... if you use a set of prebuilt proprietary binaries you just copy in place using the dump plugin you can indeed work around everything (but i think we do not want to limit packagers or force them to opensource-only software...)