Never heard of anyone trying pig skin. Crabs don't like chicken skin or fat - would assume pig skin would be similar.
If you have a source, perhaps you should try it and advise the board of your results.
I have never heard of using it but they will eat a lot of things.
Chix nx,fish,clams,bull lips and eel I think we have all heard of and used before.
I have used Chicken gizzards too with decent results on hand lines.
They used to come with the nx I think or something like that. I remember using them as a kid but I didnt buy the bait back then.