Looking at the site you linked, am I to correct that this is still early days in actual implementation?
https://reproducible-builds.org/who/projects/ https://reproducible-builds.org/citests/ https://tests.reproducible-builds.org/debian/reproducible.ht... https://tests.reproducible-builds.org/debian/index_variation...
Personally I find the Bootstrappable Builds project way more important and interesting. They are aiming to go from less than 1000 bytes of audited machine code (not assembly) plus all the necessary source code all the way to a full Linux distro. They are impressively far along already. They use multiple techniques for bootstrapping higher levels, including writing new implementations of languages written in other languages, using old versions of languages that were written in other languages etc. Some details here:
https://bootstrappable.org/ https://github.com/fosslinux/live-bootstrap/blob/master/part... https://github.com/oriansj/talk-notes/blob/master/live-boots...
Edit: some talks about bootstrappable:
In the case of Windows for Warships[0], one of the arguments (if they absolutely had to use Windows and nothing else) might be something like “Dear Mr. Gates, if you don’t empower us to do our job, we can’t guarantee that North Korea won’t retarget our nukes at your face. Sincerely, the Royal Navy.”