It's curious that in both cases you actually have to create a special app to enable any custom behavior from your phone. It would be nice if there were a bit more extensibility in these automated assistant/search/whatever thingies.
Yep this is kind of unfortunate; it's only because Google Now only resolves strings of the form "open {appname}" and doesn't provide a way (that I know of at least) to register arbitrary phrases.
It's curious that in both cases you actually have to create a special app to enable any custom behavior from your phone. It would be nice if there were a bit more extensibility in these automated assistant/search/whatever thingies.