Presumably, emoji commands will become a thing in an era when soft keyboards are the norm for personal computing devices and emoji input will therefore be easy.
More likely, such commands will take the form of a changing panel of custom ideographs. Think fast-food POS terminals.
Well... if I can input any emoji (or worse, any Unicode), then I still can almost certainly type "home" faster than the emoji. If I have something POS style, where there are only a few icons available, and the icon I actually need is part of the set, and I'm familiar with the layout so I don't have to hunt for it, then I can probably touch the home icon faster than I can type "home" - but still probably not faster than I can say it.
But you can touch it faster than the sum of the time it takes you to say it and the time it takes the machine to recognize what you said. And the touch will be more accurate.