Yes, they can canter. But they can also do some weird mixed gaits when you ask for a canter.
For instance, sometimes my Foxtrotter mare has the loveliest canter, and other times she wants to pace. Sometimes she does some of both at the same time! But she is my first gaited horse, so I don't know how to get the best gaits out of her. And she was a broodmare most of her life, so I'm not sure how much cantering she's done under saddle either. It could be that no one ever asked her to do much of that until I came along.
But yes, it is definitely possible for them to canter like any other horse. I have known of several others that will canter on the trail too.
PS. A hard pace is worse than a hard trot. It is very jarring and difficult to ride (at least in my experience). So try to get a horse that doesn't pace. Foxtrotters aren't really supposed to pace, but in my (limited) experience, it seems like many gaited horses do whatever they want, not always what they breed standards call for.