I think you are looking at only what's available in the Home Depot. Connecting to your HVAC system is "fundamentally" simple and lots of companies have done it.
"Home automation" is also not a new concept. X10 came out in 1975:
In the 1980s I spent several years defending Honeywell against some programmable thermostat patents filed in the late 1970s by one Burness C. Hall, who had aspirations to start a company. There was a ton of prior art out there. (The parties eventually settled.)
"Home automation" is also not a new concept. X10 came out in 1975:
https://en.wikipedia.org/wiki/Home_automation
What Nest had is consumer-friendliness, which I give them full credit for. Not surprising for Tony Fadell, who came out of Apple.
Oh look, now he's into crypto:
https://www.msn.com/en-us/news/technology/man-behind-the-ipo...
Maybe he'll bring his magic to that, too.