I think the valuation thing is what drives 90% of this stuff. Whereas an established company like Honeywell is more interested in building products and selling a lot of them, so they're going to charge you 5-10x of the cost of a Nest for the same feature set but with a local-first implementation instead of a cloud-first implementation.
I don't think I would ever buy a hardware product from a company billing themselves as a VC-backed startup.
Also, FWIW the Nest is a perfectly functional thermostat even if you never hook it up to their app. We found the scheduling and learning features to be really annoying so we turned them all off and never connected ours to the cloud.
A Nest is ~$150, so I'm curious where these $750-1500 thermostats are...
Seems like you get a Honeywell thermostat for almost exactly the same price, if you don't care about cloud connectivity.