C++ and Qt is a good choice for developing a mobile application, especially when you need at least two versions for different platforms. But this way is not yet too popular. Why, you may ask? Well, because there are IDEs like Android Studio, SmartCode, Xcode. It is natural to think that a native application is better than cross platform software.
The Qt development framework presents a rich set of tools for the creation of cross platform applications with an advanced UI. The framework supports all popular desktop and mobile operating systems and shares 5th-6th place in a global non-official rating of all cross platform and hybrid toolchains for desktop and mobile development.
The two main standards currently are Apple’s iBeacon and Google’s Eddystone. Also there are some alternatives like URIBeacon and ALTBeacon but it does not seem that these alternatives are particularly popular now.
One of the most common ways to make an application that reacts to natural language is to use Amazon’s NLU service Alexa. Alexa is a well known and widely used platform that analyzes a natural language, recognizes commands and passes them to an application.