This repo existed to provide unstable packages in addition to Gentoo's musl overlay.
It's transitioning into an experimental (read: mostly broken) musl overlay. The packages are slowly being moved into the official musl overlay.
Features currently not found in other distros that support MUSL include:
Icedtea requires a JDK to bootstrap it, and GCJ is broken. The two ways to install it then are to get Gentoo to allow me to host a musl icedtea-bin, or to add a hacky icedtea-bin package that downloads from Alpine.
With paludis: see Paludis repository configuration
With layman:
layman -a musl
layman -f -o https://raw.githubusercontent.com/lluixhi/musl-extras/master/musl-extras-overlay.xml -a musl-extras