You mentioned not seeing split units in the usa...I have a mitsubishi split system that provides both a/c and heat. I have a 24K compressor with three ports for the inside air handlers. Presently, I am using one 18K (living area) and one 8K air handlers (master bedroom) and one port not yet used. I do plan to install another 8K air handler in a guest bedroom. I do have central hvac although with the installation of the split units I very seldom have the need to use the central unit as I close off rooms that are not in use. In the winter months any thing below 25F I use central heating, mainly to keep the water pipes from freezing.
I'm sure you could mimic my setup, use a compressor unit with several ports and run air handlers as needed. Not all air handlers would need to be on at one time if you are not using the area. As to voltages, you will be running new electric and control cable to the compressor regardless. Might as well make it 220 vac and save a few bucks in the long run. Rgds