I understand why “C” wires on thermostats have become quite common. In addition to the Wi-Fi demand, the displays also require more energy than previous thermostats. Must admit both new features are great, but the “C” wire requirement is tough in many retrofit applications. I’m sure you have a lot of customers facing difficulty with the “C” wire requirement. Sounds like an opportunity for you??? (hint). Can you come up with a better solution than running a new, often very difficult wire back to the furnace or at least the zone valve. There are plug-in C wire solutions, but they have drawbacks.
Hope this helps. Love what “you guys” are doing.