That all varies. In California, and many other places...
The floor sink, and the mop sink must be a floor sink, there must be an air gap for the drain, so that water cannot backup into the sink. Same is true for the prep sinks. They cannot be hard plumbed.
All floors must be covered and single surface, all corners must be solid surfaced.
All refrigeration must be powered and have thermometers. No passive cooling, or passive hot holding for that matter.
Cold preparation, hot preparation, cold service/pantry must all be separated.
It does cost money, anyone cooking out of their kitchen is doing so illegally. Food trucks, especially NSF rated food trucks are a great way to have a mobile kitchen, and you can even park them at home, and work out of them. But, they are not cheap, a trailer or food truck will still set you back at least $20,000.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"I'm Armenian...perhaps...but then again...maybe not..."