Is it possible to use Rust to build GUI Android apps using the Android ndk and using QT to build GUI apps?
Your question actually is a combination of 3 mostly independent questions. Let me answer them separately.
Is it possible to use Rust with Android NDK?
Yes. It's tier 2 platform but practically it's pretty stable. Firefox uses Rust for both Android/iOS apps.
Is it possible to use Rust with QT?
Yes. Haven't used it myself, but the KDE team is actively maintaining the binding so it seems promising.
Is it possible to use QT with Android NDK?
Yes. They officially supports it.
@Hyeonu: Thanks for the info!
Is there a catch?
From my (very brief) research a short while ago, it seemed that it's not easy to create Android GUI apps with Rust (unfortunately).
Do you have experience with the workflow you mentioned?
I'm not much experienced with GUI programming, but the point is that you don't write GUI in Rust. You write GUI in QT using QML and/or C++ and call library written in Rust in it.