Nest
It's badly designed HW. Ought to be isolated contacts for 5VDC to 240V AC.
It's badly designed SW. Not just the privacy and Security.
It's from WRONG company.
IoT is garbage hype. There has been better SW & HW to control your heating & do other stuff maybe 30 years ... even for ordinary homes. The issue is always unless good at DIY, retro-fitting is expensive labour.
Labour or lack of DIY skill is why useless, insecure "wireless" burglar alarms and cameras are sold instead of cheaper and secure wired ones.
Biting the hand that feeds IT
