Oats are fine for pigs as a treat, you can make treats with oats in them which piggies like. I would be inclined not to feed them dried fruits as they are very high in sugar, which could cause mouth sores and obviously isn't good for diabetic piggies. Nuts are also an issue as they're very high in fat for a pig and can pose a choking hazard. You can give much healthier treats such as fresh fruit, grass, herb forage mixes ect Muesli isn't deathly to them however I would not feed it for the above reasons, it isn't necessary.