Is it customary to use pigs pluck to make sausages?
Historically, absolutely pig organ meats were used for sausage making. (The old joke "everything but the squeal" comes to mind.) In fact, I suspect that the notoriety of pig organs, due to their association with food adulteration, is largely responsible for them going out of fashion so entirely.

Pigs liver has a strong, distinct taste. It's used in a number of sausage recipes, but largely those which are based around it (e.g. scrapple). Lungs are illegal to sell for human consumption in a number of jurisdictions, but hearts show up in a lot of "industrial" sausages I've seen.