One problem I'm having, @mckynzee, is that Google has a really hard time understanding "Rachio." sometimes it hears ratio, or Rachael, but rarely rachio. I'm also having this problem with "ask harmony."
I speak good English so that's not it.
I think if the smartthings integration allowed treating the zones as switches, which could then be imported via smartthings like any other switch into Google home, that would be a superior mechanism for integration. Then all you'd have to say is "hey Google, turn on zone one" and not have to worry about the "ask rachio to..." bit.