...what does this even mean?
Are all the packages linked without dynamic dependencies? That doesn't seem to be the case, since maintaining build rules for enough statically linked packages would have a bus factor of way more than 0, as the project claims.
Is it that the package manager's packages are all stored in a git repo? Tons of package managers nowadays do that.
Is it that the package manager's package definition use a custom format that is not well specified and has enough features to make parsing non-trivial, just because the author doesn't want to use jq or write their own json parser in shell? How is this pile of files more static than json?
If it's none of those things this just seems like a buzzword thrown in for no particular reason.