I am using a Raspberry Pi Zero W that is running Volumio (https://volumio.org), together with an USB-soundcard to listen to my favorite internet radio stations (connected to my home stereo).
Normally, Volumio is controlled via a web interface. This actually works quite well, but sometimes it can be a bit of a hassle, if you have to open a broswer on your phone or tablet in order to just turn the radio on or off.
Luckily, Volumio provides an API, with which you can simply start and stop the last heard radio station. If you own an Android phone that is capable of NFC, you can use a cheap NFC-Tag for turning on and off the radio, just by touching the tag with your phone.
Only thing you have to do, is to install the apps NFC Tools (https://play.google.com/store/apps/details?id=com.wakdev.wdnfc&hl=de&gl=US) and NFC Tasks (https://play.google.com/store/apps/details?id=com.wakdev.nfctasks&hl=de&gl=US) on your Android phone and add the following URL-call as a task.