Virtual assistants like Siri, Cortana, and Google Assistant are only good when they're nearby. The whole appeal of these services---someday, anyway, once they're past the phase of only being good for setting timers and listening to NPR---is for them to follow you around, carrying all necessary knowledge about your life and your preferences. If the speaker in your living room knows where you live and how the traffic is, but can't tell your phone or your car, it's not much good at all.
Everybody knows this, and everyone other than Apple has the same problem. It's pretty simple: A lot of people use iPhones. The iPhone has Siri right there in the home button. How can you compete with that, when users have to download an app, log in to a thing, and then go find the right icon every time they want to use your assistant? Amazon's answer was to stick Alexa in its wildly popular shopping app, hoping people already have it on their phone. Google's is to, well, make an app and hope you'll download it.
At its I/O developer extravaganza this week, Google announced the Google Assistant is coming to iOS. The app is free and available in the US, with more countries to come soon. It does all the same things Assistant can do on Android, with one nice tweak: you can communicate either by talking or with text. Sometimes typing's just easier, like when you're checking baseball scores in a meeting or trying to figure out if that thing on your foot is benign or not.
For Google Home users, or people with Android phones, having Assistant on iOS goes a long way. But it's hard to imagine it really taking on Siri, at least in its current incarnation.
The app integrates with all of Google's other tools, of course, opening YouTube to play videos and Maps to navigate home. It'd be even cooler to see Assistant inside YouTube, Gmail, Docs, Maps, Keep, and Chrome apps. That's what Google did with Google+ back in the day---the only difference is, this time it has a worthwhile product to force down people's throats. For a lot of users, those integrations would make Assistant almost as ubiquitous as Siri.
Google did announce a software development kit, or SDK, today at I/O. That means anyone will be able to build an app with Assistant integrated, so you might start to see the Assistant pop up everywhere soon. And Google's working on making Assistant work on devices all over your life, from your car to your office to who knows what else. But still, the phone is the place. And for now, Google seems to hope you'll use the Assistant app as a launching pad, starting there and letting it take you wherever you need to go. The app looks nice, and will surely work well, but until it's as easy as a home button it's still tough to beat Siri.