I successfully used Rust to create a shared library in a Flutter project that works on both iOS and Android. So far I've only published the iOS app: https://apps.apple.com/us/app/ezmempass/id1490538369

I heavily relied on the following blog post: https://dev.to/robertohuertasm/rust-once-and-share-it-with-a...

Overall it's painful to set up and requires knowledge of the native platform (XCode/Swift, Android Studio/NDK/Kotlin), but overall it works and it was fun getting it working.

I'm happy to answer more questions about it, I've been meaning to write up the experience and details.