Is the "Radio" feature available on Denon AVR-2113? If so, where can I find it? Otherwise, are there plans to add it? As this is a really great way to discover new music, but I can't use it on a proper music device.
There is currently no Spotify radio feature on any of the partner applications, since radio is not included in the libspotify library which Spotify make available to those companies. There have been whispers of it being added for a long time, but no hard release date or solid news.
There is an ideas topic about adding Spotify radio to Sonos here which is quite popular. If that got implemented I would imagine it would become available on other platforms assuming the partner companies where willing to update the apps.