Follow up to my original post. You may commence getting hot under the collar. Google has no viable plan for functionality that Nest Protect owners will lose if you migrate to a Google Nest account.
Recieved an email from IFTTT yesterday, reminding me that a "solution" if you can call it that, for the shutting down of the Works with Nest program is to "Never upgrade to a Google Nest account, and never disconnect your Nest products from IFTTT.
Well this is not a solution. It's a bandage, that if accidentally removed, or if intentionally pulled off, can never be reapplied. Absolute nonsense. They don't even address what happens if you want to add a product. Are you going to be able to add additional Nest Protect devices to your existing account? Completely unanswered.
So I contacted Google Home support. They got scared when I mentioned Nest Protect and immediately referred me to Nest support. Nest then proceeded to waste an hour of my time while they gave me vague responses, googled for the answers and regurgitated irrelevant search results from the same generic documents I had already found myself on Google. This nonsense went on for quite sometime before the support person said, it won't work. You cannot activate lights in a Smoke or CO emergency from a Nest Protect using Google Assistant, even when the Nest Protect is on a Google Nest account and so are your smart bulbs.
So I spent the evening connecting everything I have that can connect to Works with Nest, before August 31. However, I did find a solution for anyone with Homebridge that will not be affected by the change at the end of August.