Correct. But nothing stops you from using rust today as an app developer. See https://docs.rs/crate/cargo-ndk/0.2.0
For Android you write JNI bindings with something like rust-jni.
So yes, you have to write bindings twice. For an example project check out https://github.com/dbrgn/candidateparser and https://www.reddit.com/r/rust/comments/7aam04/meetup_slides_...