Hi Susan
Glad to hear about the hog nesting under your shed and hopefully hoglets on the way soon!
I would ignore the advice on that site and stick to advice about feeding wild hedgehogs. Some of the advice there would be questionable for wild hogs. Advice was being circulated at one time that fish was not good for hogs, until someone challenged that and questioned where that advice had originated. I think that things such as chicken are meant to be easier to digest, but as I understand it, fish oil in a chicken product doesn’t do any harm. It’s probably hard to avoid, as well!
Good luck and happy hog watching!