Avoiding certain meats may be more complicated if you are extremely sensitive, for instance, even certified vegan products can be made on the same line as meat and milk products. People who avoid meat, for religious reasons, often have certification measures that are more restrictive.
For Jews not eating pork is the most observed kosher practice. Muslims consider eating products derived from pork violation of their dietary laws as well. Muslims mark products that comply with their dietary laws as Halaal meaning “lawful” or “permissible”. The foods that meet Jewish dietary laws have Kosher labeling. Both are “pork free” with almost no cross contamination issues with pork.
Jewish people who observe dietary laws do not mix milk and meat. If you are also allergic to milk, be aware that in Jewish law, a food product may be considered pareve, if it contains a very small amount of milk. Food marked parve could potentially have enough milk protein in it to cause a reaction in a milk-allergic person.
Most halaal gelatin is made from beef not pork so it can not be considered vegetarian.
Hidden Pork usually in the form of gelatin includes marshmallows, candies, ice cream, jello, vaccines. There are vegan and Halaal variations of marshmallows, jello and other foods. Making Vegan marshmallow or gelatin is difficult to make, and also hard to find.