init is a binary executable.

binwalk did not extract any meaningful data from it. init has got quite beefy. Other files which had previously been included in the initial ramdisk in earlier android versions have been pushed out onto the system.img under /system/vendor/etc/ in case you were wondering.

link to aosp readme: https://android.googlesource.com/platform/system/core/+/master/init/README.md