Google announced the end of support for early Nest Thermostats in a support document earlier this year that largely flew under the radar. As of October 25, first and second generation units released in 2011 and 2012, respectively, will be unpaired and removed from the Google Nest or Google Home app.
Users will no longer be able to control their thermostats remotely via their smartphone, receive notifications, or change settings from a mobile device. End-of-support also disables third-party assistants and other cloud-based features including multi-device Eco mode and Nest Protect connectivity.
Simply, check for cloud dependency; can you set it up without the thing’s app, without internet? Does it keep working when the internet is down?
Thread and matter can have “unique” implementations but it’s better than proprietary.
Also, if it works on multiple, competing platforms, it’s likely following an open standard. Can you use a mix of devices from competing companies on a third, competing platform? If so, you’ll probably be fine.