So the other day I bought a google home. This provides a standalone device with the google assistant (which also lives on my phones and tablets).
I run 'homeassistant.io' which allows me to manage some of the various and sundry things around my house. E.g. turn lights on, whatever.
OK, now I'd like to introduce the one to the other. The platform of choice for this is 'IFTTT' (If This Then That, pronounced like gift without the g).
I would also like to be able to push notifications from it to my devices. The platform of choice for that is Google Cloud Management (gcm) push notification, integrated with homeassistant.io via the 'notify.html5' method.
Wow, this was much easier than I thought. No programming is needed, a few simple web clicks. And now i can turn my lights on and off by voice from anywhere in the world.
This 'ifttt' platform is a lot like SandScript. "If this then That", hey, that is SandScript in a nuthshell. It allows inbound 'conditions' and outbound 'actions', its a cloud-based policy control system!
They've been working on the problem of the "OK Google" and a bunch of devices wake up problem. Its not perfect yet, but better. If my phone & tablet and 'home' are in the same room, usually only the 'home' will wake up.
Now, for security. There are API keys everywhere here, and OAUTH2. The security model is they all meet outside my house (that is, until I start hooking the mqtt ones up, for that i'll run a local broker I guess).