The repo is here, and you can directly build it as a regular Flutter project.
Unfortunately, the SyslabCC released for public use currently does not work with Flutter Windows/macOS build. You might just use the Android build, or build it under some Linux distro.
The built APK is a small scientific app for running heat equation simulation. The callsite of the Julia function is made in Rust (using Rinf) at here, which is simply a ccall in Rust.