From looking at the the Java files in the linked tarball as well as the documentation[1], it seems that PicoLisp calls Java by sending serialized messages through pipes from a separate processes and then invokes the Java reflection APIs.

So trying to use this to build an Android app with the native (i.e. Java) Android UI libraries probably wouldn't work too well, right?

[1] http://picolisp.com/wiki/?javacode