You can run the build process of any Debian package you want. It is quite easy to reproduce a functionally identical package. What is hard is too reproduce bin

You can run the build process of any Debian package you want. It is quite easy to reproduce a functionally identical package. What is hard is too reproduce binaries that are byte-for-byte identical. This is not really needed to debug or work with a system, but needed for security to assure that no-one has meddled with the binary. If you think source package distribution are more useful than binary distribution, then Gentoo Linux is still a viable option.