A Muslim trader is allowed to trade in all things according to Islamic law apart from the things which are forbidden, including pork. It is forbidden for a Muslim to sell pork to Muslims, non-Muslims, in Muslim countries and non-Muslim countries, even if his shop is specifically for selling permissible things. Whoever leaves a thing for the sake of Allah, Allah rewards him with something better than it.
Sheikh Ja’far Al-Talhawi says: There is no harm in buying and selling foods, according to the saying of Allah SWA- (Allah has permitted trading and forbidden interest), so the ingredients that are used to make Pizza there is no harm if the Muslim combines them and develops them into something nice, on the condition that these foods do not contain anything that Allah SWA has forbidden to eat or drink, as Allah (SWA) says: (Prohibited to you are dead animals, blood, and the flesh of swine)
This is what distinguishes a Muslim from other tradesmen. He advises his customers in speech and action, as the religion is advice. He doesn’t offer what Allah has forbidden to his customers, or what may harm them. The rulings for what is allowed and what is forbidden in the Islamic law are built upon benefit and harm, and Allah did not make something permissible but it is beneficial, and he has not forbidden something but it is harmful. Allah SWA says: (They ask you what is lawful to them. Say: ‘The good things are lawful to you). and He says (This day are (all) good things made lawful for you).
It is not necessary that a Pizza have pork on it, it can have any other kind of meat that Allah has made permissible and lawful for you, and the Muslim has a way which distinguishes him from other restaurant owners who are non Muslim, by the cleanliness of his restaurant, good cooking. He finds what people like which makes them want to come to his restaurant, from what Allah SWA has made permissible, and he gets the satisfaction of Allah SWA, and receives blessings in his earnings.
It is obligatory upon the Muslim to stay away from copying the practices and monopoly of non Muslim restaurant owners, those who offer what Allah SWA has forbidden to their customers, to satisfy their desires, and to earn large amounts of money even though it is through forbidden means.