Google Assistant is clever -- just ask Pixel or Home owners. Unless you're using Allo, though, you have little choice but to ask the AI questions through voice commands. Google might give you more ways to interact in the near future, however. An exploration of the Android search app's beta code has uncovered hints (namely, a keyboard icon and a text box) that you'll soon have the option of typing your Assistant searches. This is important if you'd rather not reveal your queries to everyone within earshot, but it should also be key to integrating chat bots.
It might be easier to start a search, too. There are references in the beta to "search gestures" that suggest you won't always have to tap the search bar to start asking. Instead, you'd swipe down from the home screen. That could be particularly important for very large phones and tablets, where it can be a pain to reach across the display.
Don't count on the relevant upgrades showing up all that quickly. Unused code frequently pops up in Google apps, and it can take months or more for those features to be ready for prime time if they aren't canned outright. Both additions are very logical, though, so it's doubtful that Google will keep you waiting for too long.