https://ionicframework.com/docs/native/music-controls/ https://ionicframework.com/docs/native/speech-recognition/ https://ionicframework.com/docs/native/httpd/ https://ionicframework.com/docs/native/http/ Utiliza la librería Bluetooth Serial, y el estilo de ionic 3.
La librería no está optimizada para conectar dos dispositivos con android.
Para descargar usa:
$ git clone https://github.com/jlozoya/ionic-bluetooth-serial-example.git
$ npm install
$ ionic cordova run android --device