If you have any doubt in the food stuff of any company like pizza and other things whether it is halal or haram then two pious and religious Muslims should visit the company and observe what ingredients are used to prepare the same. So, if any haram thing is used in any food then it shall not be lawful and halal to eat, sell it as per the Shariah. But if you learnt after the observation that no haram ingredient was used then eating and selling is lawful. Yes, if there is any doubt in the adulteration of haram then you should avoid it.
دع ما يريبك إلى ما لا يريبك!
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband