You can write fully native applications, here's an official example:
https://developer.android.com/ndk/samples/sample_na
It is a very simple example of a purely native application, with no Java source code. In the absence of any Java source, the Java compiler still creates an executable stub for the virtual machine to run. The stub serves as a wrapper for the actual, native program, which is located in the .so file.
I don't know how LispWorkds does it, but there's no reason it couldn't do something similar. Compile your parentheses down to AArch64 or whatever and have it wrapped in Android's mannerisms.