I would specifically get a clarification on the first-floor system. I am not familiar with other than OEM smart thermostats that could handle a multi-zone inverter system....that is multiple indoor units served from one outdoor unit. If you are not careful with these multi-zone inverter systems you can have problems with oil return and even burn out the compressor. Usually the thermostats in these systems are communicating type thermostats by the same manufacturer as the equipment, eg. Daikin, Mitsubishi, LG, etc.
If you have a typical installation with one indoor unit coupled to one outdoor unit you usually would not have these issues.
I would discuss this with your HVAC contractor and advise him that you are considering installing smart thermostats and get his opinion. After all, he is the one who is going to warranty the systems.
