Has anyone else in Florida come across anything like this? A braided stainless steel connector on a public water main?
Why would you think this is a “Main”? I would bet it goes to an outdoor water feature, pool, backyard wetbar, etc.
There’s no question it’s the water main. When the valve is closed, all water to the house is off. Also, it’s on the corner of the house nearest to the in-ground meter.
I don’t trust them on a water heater, let alone the exterior main supply (if it is the main). I have seen a few of those things burst on water heaters. They only have an expandable rubber hose inside.