The Apple Watch can do it today. (In iMessage, as one easy example app, there's an entry box to send a new message. If you tap into that and get a keyboard cli

The Apple Watch can do it today. (In iMessage, as one easy example app, there's an entry box to send a new message. If you tap into that and get a keyboard click the keyboard icon in the bottom corner and there's a "moving finger" icon you can tap to get a trackpad to draw letters on. Older and smaller Watches won't even have the keyboard and will just have the trackpad.)