The video calling capability seems especially neat - I wonder if they will interoperate with Facetime, Google Duo/Hangouts, and other video calling protocols. It will make our lives so much easier.
If anything, it's looking like Alexa might be the only one that will work across the 3.
You can install hangouts duo on IOS, but likely not on alexa. You can install Alexa on Android (not through google play). You can't install facetime on Alexa or Android.
