Slave thermostats or control relays for mini-split cooling

Some of us have homes that were built with baseboard radiation for heat. When cooling is added, often, now, it is in the form of a mini-split system, or variable refrigerant flow multi-zone mini-split. These systems usually have their own thermostats, which cannot be used as a smart thermostat. They are mounted in a different location in the room. Also, the voltage source is separate, so connecting both to the same thermostat is difficult. It would be really nice to have both the heating and cooling coordinated, and visible on the app.

I can think of two ways to solve this - the easiest would be to have a second thermostat in the room, operating as a slave to the first. When the setpoints on one are changed, the setpoints on the other are changed by way of communications. A slave thermostat could be identical to your current thermostat, or it could be faceless, without a user interface. There are other wishlist posts about thermostat groups, where changing one setpoint changes all in the group. This might be almost the same - just set up a two thermostat group, and wire one to the heating, and the other to the cooling.

A second, less desirable way, would be through the use of slave relays that could be bound to the cooling output via communications.

Many of the mini-split systems also have a reverse-cycle heating mode. At moderately cool outdoor temperatures and up, they operate more efficiently than the boiler, so it would be desirable to use this as the first stage of heat down to a user-definable interlock temperature, which would disable the mini-split heating mode when the outside air temperature was too cold. Maybe better, switch the mini-split heating mode to become the second stage or fallback heat, which would only operate if the boiler could not carry the load for some reason, such as boiler failure.

Benefit to your customers would be to simplify the smart operation of separate heating and cooling systems. Benefit to Wyze might be to increase the number of units sold.