What device? "Google Assistant" is a technology. Implementations exist on phones (both Android and iOS), laptops, and many other devices.
You seem to be getting excited thinking it refers to a specific piece of hardware you'd have to buy. It doesn't.
Then "YOUR" options are REALLLLY SIMPLE......just use the app that is directly linked to the Nest device ONLY....that IS YOUR OPTIONS, given the flexibility you allow.......problem solved!
Is it tacky to re-post this here?? 
As I have mentioned previously (perhaps I'm a conspiracy theorist), I believe that this is but the first step in an incremental effort at Google to make their device the centre of IoT control in the Home.
Google assistant works just fine without an actual Google voice assistant device. You can issue voice commands directly from your mobile device.
Check out my thread from a while ago - a lot of good advice there.
Personally, I've compromised on my desire to have everything centrally controlled in favor of "purpose built" products/systems, favoring local control where possible. Google dropping Nest API was the nail in the coffin for going with an Ecobee4, which I have been extremely happy with -- perhaps because I'm choosing to let the thermostat operate on its own and not through HE. Ecobee was already the better themostat, ignoring any cloud issues.
I do have eight nest protects, so this news is still a bummer because I had them integrated with HSM. I believe that was still dependent on the cloud, so not like it could be called dependable. I'll probably do the same automation (turning on lights) through Google Assistant.
For cameras, I ended up with a Ubiquiti Cloud Key Gen 2 Plus and a couple of cameras for the time being. 100% local but with (very fast) cloud access. I've been very happy with it, a big leap up in performance and likely privacy over the Arlo camera that it replaced. However, it does have shortfalls (currently no setting to receive notifications only during certain times), and I'm not sure it's worth the cost unless you buy other Unifi network gear to take advantage of the controller.
Entertaining as always; Paul Hibbert has a youtube vid about the Nest API shutdown.
Lol that’s a great video.
It does raise the question, if Google believe Nest is a risk to people privacy and security and are pulling the plug from IFTTT and everyone else, then surely they would also pull the plug on APIs for such things as Gmail, Google Drive, Calendar, Contacts etc etc as these really do pose a privacy risk. I guess we shall see soon enough - if IFTTT starts scaling back Google integrations forced from Google then there really is the concern from Google for privacy. If they don’t, well, pretty obvious at that point what they are doing
https://www.androidpolice.com/2019/03/22/most-ifttt-applets-using-gmail-will-break-this-month/
From March: “IFTTT says it discussed these changes with the Gmail team, but ultimately decided that it couldn't keep most of its existing functionality without "major infrastructure changes." As such, every IFTTT action and trigger for Gmail except 'Send an email' and 'Send yourself an email' are going away soon.”
This is just a vague post from a Google social media person, but their response to me does at least hint to some more functionality being added to Works with GA.
But, I suspect that "similar integrations" are going to end up meaning one-way (from GA to devices).
I'm taking a wait and see approach. Sure, I could get all upset and spend a bunch of money replacing my Google hardware.. but if this is all a misunderstanding or if Google throws the industry a bone after all this backlash, I'll have spent a bunch of cash for no reason.
Things work for now. I'll revisit things later this year.
I doubt that it's a misunderstanding. Google should have anticipated some backlash and likely weighed the risk versus the long term revenue benefit. This is a power-play to cripple access by competitive products.
My only investment in nest has been 5 nest protects. But I was looking at a couple of nest hello devices. And while I'm certainly not going to run out to replace the protects, I won't be buying a nest hello or any other nest product until there's more info about how this is all going to pan out.
Oh I don't disagree at all. I'm just saying that we have very little information on how the Works with GA stuff will actually work. We have educated guesses, but they are just that. Maybe we're guessing wrong? Small chance, but still a chance. Maybe Google anticipated lower backlash? Perhaps, but I don't know for sure.
Some people in this thread seem ready to throw out their entire smarthome, burn their gmail account, and launch their Android phone into space. I just recommend waiting for more info before nuking your google existence.
Ecobee is supposedly working on a new thermostat and it has 900MHz radios in it:
Yeah, well, Ecobee has a vote of no confidence from me after their demonstrated cloud unreliability. Even if they make a more 'local' version now, they have lost my trust, which is not easy to gain back.
Not for everyone, I get it, but HomeKit is local integration already available on Ecobee.
True - if you are an Apple disciple. Which I'm not. 
Don't get me wrong, more options are GOOD - and different solutions are the right choice for different people for very valid reasons.
I for one am glad there isn't only one viable option out there.
Download the Hubitat app
