Unfortunately it’s not (yet). Amazon’s official SDK only supports the development of skills, not direct voice interaction. They’ve also released some code to allow direct voice interaction, but they have changed it so many times (first it was a hackish Java-based application, then the avs SDK, then they dropped it in favour of the avs_client, and recently they’ve dropped it in favour of the alexa-client…) that I really didn’t feel like investing much time in building an integration that would have been broken a couple of weeks/months later.
However the alexa-client package has been around for almost a year and it might be stable enough that I could build an integration without feeling that I’m wasting my time. There’s an open issue to keep track of the progress: https://github.com/BlackLight/platypush/issues/80.