As I believe that I have mentioned before, I just finished a self-installed central air conditioner system about two weeks ago. The unit is ducted, but based on ductless inverter compressor hardware.
The system came with a proprietary digital wired remote, as well as an infrared remote identical to the ones shipped with ductless units. The manufacturer also provides on/off dry contacts for use with an old-school thermostat, but strongly discourages using them for a thermostat since you will lose all of the benefits of the inverter compressor. In other words, the shiny Ecobee smart thermostat hanging on the wall for remote control of the baseboard hot water heat is not much use with the new AC unit.
The “attack vectors” for controlling the unit remotely are the IR interface, and a Modbus-type screw terminal interface for connecting to a commercial building controller that isn’t sold in North America. The manufacturer’s recommendation is a China-sourced wifi IR remote that they sell, with no integration into anything but their phone app. (Did I mention how much I loathe IR for remote automation, since it does not provide feedback that a command was received?) I am resolved to rolling up my sleeves to see if I can figure out the Modbus-type protocol on an Arduino or Pi, but needed something fast in the mean time.
Tado is having a clearance sale on their Smart AC controllers, since they are about to launch a new generation. The other option is $1.00 cheaper for a Sensibo, but my preference is for Tado because they are located and manufactured in Europe with no ties to non-existing privacy laws and cloud servers in China. It interfaces to all of the usual suspects, and there is a third-party HomeBridge driver available to let Siri control it.
In terms of looks, it blends into a white wall really well…until the LED display illuminates. Then, you are greeted with a grainy dot-matrix attempt at icons that will make you wish for a Davis weather console since its 1990’s LCD is more clear! 
In its defense, the Tado has a few capacitive touch hotspots, whereas the Davis will never have those.
The Tado unit comes with two control modes. In the simple mode (thermostat control), it uses its internal temperature sensor to turn the AC on/off via IR. This requires scanning only four settings from the factory remote - lowest/highest temp cool, and low/high temps heat. I will let you figure out how this is better than simply hard-wiring the Ecobee to the dry on/off contacts, since it looks like it will have the same problem of not utilizing the inverter compressor to save energy. The other mode (non-thermostat) uses the AC unit’s internal temperature probe, which makes the inverter compressor happy. To use that mode, one simply needs to sit in front of the Tado for an hour and a half pushing every possible temperature/fan/mode option into the factory remote to teach the Tado what it should already know out of the box. By the time that I finished, the first thought that I had was that it would have been faster to decode the Modbus interface than program the IR remote codes!
Long story short, I have the HomeBridge plugin set up, and Siri can control the AC from my watch. I am not ready to declare this my favorite gizmo right now, but will give it a few days to see if the IR loses sync or the unit annoys me enough to smash it to bits… 
aside.
