No, not really, or at least, not comfortably. I tried this with my 12.9 (with the same keyboard, the foldable one) for a few days on the train and it is possib

No, not really, or at least, not comfortably. I tried this with my 12.9 (with the same keyboard, the foldable one) for a few days on the train and it is possible to balance it on your lap while sitting nicely with your legs bent at the knee at a 90ish degree angle, feet flat on the floor. The keyboard is stiff enough as long as the gulf between your legs isn't too wide. The problem is that any shifting around can cause this set to move and tip. It just doesn't feel long-term stable. It is possible to do it for a few minutes, say, to reply to an email. That said, the keyboard is really nice to type on and is really easy to get used to. I know these things are very subjective.