Reinstall different base of void linux (musl/glibc)

Reinstallation isn't that terribly difficult:

Grab a list of all manually installed packages xpkg -m > pkglist.manual with the xpkg tool from xtools) and the list of all packages xpkg > pkglist.all

boot with a Live CD, mount your target system at /mnt)

uninstall all packages xargs xbps-remove -RFf -r /mnt < pkglist.all - the idea here is, that any file you did modify (thinking mostly about /etc/ here) will be preserved.

move the old xbps package database out of the way ( mv /mnt/var/db/xbps /mnt/var/xbps.old-musl)

Reinstall the packages from the glibc repo xargs xbps-install -yAS -R http://auto.voidlinux.org/current -r /mnt base-system < pkglist.manual

As long as you don't steamroll at installation (-f your modifications should be preserved).