Pig Gelatin
if its chemical composition changes, then it is halal.
Whether or not the gelatin used in certain products has really changed it’s chemical composition is for the food / chemistry experts to decide. From the jurisprudence perspective, if something has lost its chemical properties to become a new substance then it’s not bound by the same sharia laws. There can be differences of application in this matter and one should follow whatever they find the right approach. Personally, I don’t think that one can go wrong erring on the side of caution, but one should not be overly sensitive to this matter.