Cross-compiling for Android is well-supported on many host platforms, including Linux, Windows, and macOS. Besides Qt for Android, on your host machine, you will need both Android's SDK and NDK. Especially for NDK, you should make sure you install a version that is supported by Qt for Android, as the used NDK gets updated less frequently than the SDK. For Qt 5.9, the recommended version is 10e. For complete requirements, take a look at http://doc.qt.io/qt-5.9/androidgs.html. An introductory video about Qt on Android is available at http://bit.ly/QtAndroidIntro, and one covering more advanced topics is available at https://www.kdab.com/all-about-qt-on-android/.