If all else fails, get yourself a pair of sleep headphones. You know, those headband things with flat speakers inside. Play white noise, rain sounds, or a boring audiobook. White noise is a miracle worker—it masks the snore without ruining your hearing.
You can even record their snore one night and play it back to them over breakfast. Warning: This may lead to a fight. But it might also lead to them realizing, “Oh wow, I sound like a dying engine. I should try that nasal strip.”