As to metabolic compatibility, we can’t even eat everything on Earth. And vice-versa, thank goodness. There are so many types of carbohydrates, proteins, and fats. Some are essential, many are digestible, some are not digestible, and some are toxic. I don’t see it being different on any planet where the life started from the same building blocks we started from. We just have to be able to tell the beefalo from the puffer fish.