What is the ruling on consuming foods that contain gelatin or pork derivatives, the source of which is difficult to determine in non-Islamic countries?

Gelatin made from pork is Haram (definition) (forbidden) by consensus. If its composition does not include anything forbidden, then it is Mubah (definition) (permissible). If its origin is unknown, then its use appears to be permissible due to widespread affliction (عموم البلوى) and the unknown origin, and because most manufactured materials have been processed to the point of transforming from their origin, and because the default ruling for things is permissibility. Pepsi drinks, yogurt, potatoes, and other similar items are originally permissible until it is proven that they contain something forbidden.