sliced turkey would be fine with chopsticks if either thin enough to bunch up like coldcuts, or further cut/ripped into chunks, whereas roast vegetables can also be chunked. and all the rest arent even fork foods?? theyre spoon foods for sure, the spoon gives more scooping surface area, more carrying capacity, and the sides slope up to prevent stuff falling off. if your mashed potatoes are self adherent enough they dont fall out between the fork tines, then theyre liftable via chopsticks (and if they arent then theyre drinkable)
i could see an issue maybe if you put peas, decobbed corn, or nonadherent rice on a flat plate, then chopstick shoveling might present an issue sure, but at that point its not the fault of the chopsticks but rather the choice of dishware. put em in a bowl and lift to your face, *then* shovel w/ chopsticks only just separated enough so nothing passes between for optimal shoveling, easy peasy if youre good at chopsticks.
maybe we should assume for the sake of argument that choosing chopsticks instantly grants you chopstick mastery if not already possessed (and vice versa for the other cutlery)
also cheetos and other powdery snack foods are definitely not able to be picked up with a fork, much like sushi, whereas chopsticks manage fine. and i dont like getting dust on my fingies