I would never buy an appliance that requires a third-party server. Google cannot remove the value from a Zigbee or Z-Wave thermostat like this.
Other major reason being that "IoT" devices usually have the shittiest WiFi radios that usually don't even support 5 GHz and almost never support WiFi 6/7 modes where they aren't wasting a ton of airtime on their low-bandwidth communication.
I have a pair of Govee ceiling lights that have a RGB+CCT primary downward facing light and an addressable RGB accent ring. The ARGB ring only exists in their app. As far as both their Matter support and their official API are concerned these units have a single element which is the downward light, the ARGB ring is not controllable from any third-party systems.
If these were using Zigbee, Z-Wave, or Matter over Thread they wouldn't be able to do this but because they use WiFi they can.
I'm going to be opening one up soonish to see how hard it'll be to just replace the controller with one running WLED (or even reprogram the controller already in it).
The easiest way to avoid that problem is to just skip retail WiFi devices altogether because having WiFi basically always means assuming internet connectivity which is not far from mandatory cloud bullshit.