The skin of animals not allowed for consumption also becomes clean (tahir) if it is slaughtered according to shariah or by tanning and its external use is lawful. But the pigskin is exempted. Hence, you need not to have unnecessary doubts. Yes, if you are sure about any article by shariah research that it is made of pigskin, then its use is not lawful.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband