Training classes work well for dogs (and owners) also because they get to watch other dogs interact with their owners and with other dogs. Social skills and stuff. I suspect that getting dogs more exposure to others also helps them deal with separation anxiety, such as when we go to work.
To train a dog to enjoy a chew toy, have your dog watch another dog have fun with it.
If you have the right kind of chew-toy, some dogs also really enjoy a good tug-of-war.
Also: IMHO it’s a good idea to give your dog a “sanctuary”: someplace they can go where they know they won’t be disturbed, and someplace they can retreat to if they know they did something wrong. My parents typically use a decent-sized dog travelling crate, depending on the size of the dog. Once you establish one, it’s important to not disturb them while they’re in it outside of dire circumstances.