Google supports iOS pretty well. They don't support Windows Phone at all, but I've heard a lot of Android users complaining at various points that iOS gets the app updates quicker than Android does for some Google apps.
And there's probably a lot of overlap between Apple's customer base and Nest's. I'm not saying they won't do it, I really just mean I don't know how likely it is :-)
And Nest is owned by Google, so I'm not sure how likely that is.