Nostalgia is a nuanced word that takes some thought to explain, and we can’t really communicate with them to ask the kinds of questions we need to in order to get that answer.
But it’s well documented that dogs remember humans and other dogs for their entire lives, and that in my opinion does indicate some kind of retrospection.
Whether they feel it the same way we feel it is something we can’t know. But they probably think about it from time to time if it’s not overwritten by new memories.
Yeah this definitely feels like they’re just trying to bring them out of hiding so they can start exterminating them again.