I finished this draft version of my Smart app that uses Virtual Dimmers to adjust a thermostat’s temperature setpoints for heating and cooling. Although there is a short lag, the app will also adjust the dimmer level of the virtual dimmers if the setpoints are changed directly from the device. I also added options for a setPoint limiter for maximum/minimum. This way temperature setPoint request is out of range it will reset to the preset maximum/minimum.
As you know you will still need to create your own virtual dimmers switches to link to this app,
Please let me know how it works for you.