Many of these packages/ebuilds will have patches to make things work on a hardened-musl system. Such packages are likely temporary in nature and will become obsolete (and probably get removed) when the official hardened musl adopts the patches or upstream fixes their code. There is a small chance that some of these might be poor quality patches that are good enough for my purposes, but would not be acceptable in the hardened musl repository.
Other packages/ebuilds might be used to track specific git commits in an upstream project.