Yep. I remember how at least JDBC and JWT libs were needed to rewrite using a native language (which we did until some point!). And the GraalVM has a weird API that is not JNA/JNI when you want to use the native-image. It is not very robust system for our needs, but it was a good learning experience.
What we did in the end is we rewrote parts of the system with Rust, plugged that to the JVM package and we had all our tests ready to use. First the database connectors and at the same time the other part of the team was writing the graphql parsing in Rust. We could all utilize our Scala integration tests which was crucial for our success.
And btw. we still have our tests in JVM, although the rest of the stack is Rust now.