The Google Pixel 2 was recently said to have the best smartphone camera now available, according to DxOMark. So you can ask Google Assistant to find you the nearest restaurant where you now are or ask her to dictate to you your schedule for that day or to open an app for you on your smartphone. Anyway, this is a really handy trick, as it narrows the differences of what you can do with Google Assistant on different devices.
If you are more interested in the updated Google Camera, I'm sorry to say that it looks like you'll need a Google device to make it work. As you might expect, the new cases are meant to be slim, high quality, and also capable of withstanding drops while also meeting the MIL-STD 810G standard. If you tried to do the same with Assistant on the phone though, you were greeted with an error message. A big example of this is when you're trying to play something on a Chromecast device.
Google Assistant on your phone got a lot more useful with controls for Chromecast now live from your phone.
As the company continues to work out these little (but many) discrepancies, it shows that they're not giving up on the problem and continuing work to improve the user experience. But with 30 seconds of work and an Android phone, you can pretend like you've got Google's newest flagship, thanks to the release of the Pixel 2 default launcher. You should be able to send videos and music to your Chromecast-built-in devices even if you don't own a Google Home, but at this time, it's not clear as to how the functionality is being rolled out.