Each a house is best. They do need place to run, so their cage needs to be big enough. Also, a house needs at least one big entrance, that fits 2 pigs in one go, as the boss pig often chases another pig out, or 2 entrances.
Don't bother with store bought houses. Go to Shopko and get two plastic children's stools that have 4 entrances. Pigs will use them as hideys AND can race through them when doing zoomies. And their washable.
Most pigs don't really play with toys that much. The best plaything is having another pig in the cage to interact with.