@lispi314 @nytpu I think another way to become resilient against link rot is to have all the source code of the packages you use in one place.
There used to be source CDs but most distros don't fit on a CD or a DVD anymore. So either mirrors like Debian does, or keeping the source code of everything you install on your local disk (or a NAS).
A while ago I was of the opinion that Gentoo users are uniquely well prepared for an apocalypse, but that may've changed recently