Here at QuestDB we're beginning to write part of our database code in Rust as JNI native code extensions. Since all of our Java code is built with Maven we found we needed an easier way to invoke `cargo` during our normal build cycle. The plugin makes it easier and has a few extra features such as running tests.
If you also have a Java code base you're thiking of extending with Rust, we hope you can find this project useful.
I think there's possibly some automation that can be added once that whole stuff stabilizes properly. From Rust it's already possibile to automate exposing a C header via cbindgen, so it wouldn't be too hard.
JNI ultimately still provides the most complete set of capabilities (e.g. calling back into Java).
For the rust-maven-plugin, we've accepted a PR to build binaries and we'll continue accepting PRs for any future enhancements such as the one you're mentioning.
FFI - we need to wait and see how this actually evolves.
We are not looking at any of this just yet. While it is undoubtedly fun, there are few other things we're busy with.