ahah ) as a current "wishmaster" wanna say that most of theese packages are not depend on kernel, so you can take it from openwrt trunk (compiled with musl)
also in case of extroot it's possible to arrange entware installation for the witi. Entware packages compiled with static uClibc-ng and don't care about specific mips platform (so in general mipsel branch should work with any mipsel SoC).
I don't have my own build server, im using a 3yo amd a8 laptop, so building so many packages will take time which i don't have
Probably in future i will release a build with all packages built (as openwrt buildserver do), but only after polishing current lowlevel things.