Honestly you will be better off buying a system designed for a restaurant rather one for use in a home.

they have budget issue we initially offer QSC Core Nano but they already say need alternative they can’t afford the system

In my opinion SONOS is great at home, but not great in a restaurant.

I would get a 3rd party multizone amp(s) for that sort of setup.  You don’t need 9 different zones, and it would not give you volume control at each speaker..  I would imagine that you typically would have just one source with volume control for each speaker that remains pretty constant.  If you want the ability to use Sonos to control the source, then you add a Port or two.  Not counting the speakers and wires, you should be able to do that for under $3500.  9 amps would cost you $3600.