I did a bit of a search, and I was shocked to find that there's nothing like this for Z-wave or Insteon.
Eve Aqua HomeKit compatible garden hose valve.
Or am I just not searching by the right thing? I know there are all sorts of z-wave valve shutoffs, but if the wacky guy who built your home used standard turn spigots instead of 90° lever valves, you're out of luck like I am.