Dracut looks to replace the initramfs patchwork

That is because initramfs is extracted to the 'rootfs' (some instance of an ramfs), and rootfs is not supposed to be pivoted. Instead, you remove all files and then do a normal chroot. In other words:

$myothercommands;
LD_LIBRARY_PATH=/mnt/lib /mnt/lib64/ld-linux-x86-64.so.2 /mnt/bin/rm -Rf /$everythingButMnt;
exec /mnt/lib64/ld-linux-x86-64.so.2 --library-path "/mnt/lib:/mnt/usr/lib" /mnt/usr/bin/chroot /mnt /sbin/init "$@";

something like that. Of course you can wrap that into a nice C program, but if it works without, you'll probably spare the extra binary.