TL;DR: you need a smartphone to run Alexa.
Why couldn't they do this exact same thing with Alexa? And from what I read you need to provide your own SIM to get Alexa working, why would that be the case if you were required to use a phone?
Or Pebble Core :). Which seems to be intended to let you leave your smartphone at home when you go outside.
But I can't wait to use it as a companion. Google Now generally sucks, and the only way I found to make it usable is to hack it with Tasker. I don't mind carrying Core all the time, along with the smartphone.
(I just need to figure out how to keep it alive for the whole day with the 3G always on.)
That said, I'm more interested in figuring out how to get offline speech recognition running on Core with something like PocketSphinx and only relying on the 3g connection when needed.
All this has got me thinking about what the smallest Android boards/devices out there are and how I could get a Raspberry Pi Zero connected to a cellular network. Need to do more research on this.