You must use a kernel with the android-specific modules compiled in, or use the binder_linux-dkms module. I've noticed using a kernel with them built in is generally easier to get working.
The app ran super smooth as if it was running natively
That's because it is native! Waydroid runs an android container on top of your existing kernel. You will notice that you can even see the Android processes while running Waydroid in a top utility.
I can confidently say that the answer is "SYNTAX ERROR."