Depends on how long a tournament lasts.
I think dry snacks are okay or using an utensil, but it can get messy for my mousepad on my laptop if I eat a sandwich or finger foods that are messy or greasy. If can play on my phone (only some sites have mobile capability), then it is no problem to just wipe my phone with a mildly damp soapy cloth when needed.
It is also helpful to have a light meal before the tourney begins, so hunger won't distract me, especially if I am multi-tabling.
I also keep beverages nearby, so I don't have to rush to grab them between
hands, as I like to watch the action even if I am not in a hand.