Rust Programming

I don't do Android (or much UI in general), but from what I gather, going with something like flutter_rust_bridge or membrane is probably the best route. The UI is not done in Rust. But it's as close as you can get for non-toy use-cases, and without bringing a JVM language into the fray.

Toyota people apparently developed membrane for serious production use. But I haven't used either, so I don't have first hand experience to share.

I've not heard anything about the NDK being deprecated and nothing on the website seems to indicate it is so in theory as long as your Rust code exports C FFI bindings you could call it using JNI. You'd need at least a minimal Java/Kotlin wrapper and most of your UI would probably end up being done on the Java side of things, although in theory that isn't strictly necessary. There's a cargo plugin (cargo-ndk) that automates a lot of this process.

As one example the Bevy game engine supports iOS and Android targets and doesn't use any native UI elements instead using a GPU canvas (I'm unsure if the implementation is Vulkan, OpenGL, or something else like Metal on iOS) and hooking the native touch controls.