I had a Nest thermostat (before it was gobbled up by Google) many years ago in a home in New Hampshire. It ran a furnace that burned supposedly eco-friendly pellets. To be honest, my only interest in the furnace was that it offered an economical alternative to the established expensive centralized gas utility. The thermostat was sufficient. I never used the phone app designed for it because the house was too small, and I saw no benefit in adjusting the temperature of my house while at the grocery store.