I don't know if i can offer any help or not. I've never had a sight hound that would fetch or carry. But I have owned a lot of sight hounds and I think you will get a lot further with polite requests.
My sight hounds have always complied with polite requests, but give them an order and they stare off into the distance and ignore you.
With my collector GSD, I had her bringing me things all day long. it was vocabulary building, not an attempt to stop her from collecting. But she loved it, and it did teach her to bring me any treasure she found. Bring me your spinning bowl, bring me Daddy's socks, bring me your squeaky squirrel, go get in Daddy's chair........ It kept her busy and burning off energy.
Then, if she had something she shouldn't, I would "trade" for it. No disappointment. I would just say, oh, you don't want that. Come here and trade. Then I would praise her for the new item and start a new game with her.
She would choose one family member and collect all their small items after we went to bed. It taught the child to pick up after himself if he didn't want to retrieve his things from the dog's bed in the morning. Just one person per night, but we all got a turn. I never tried to stop her, but if I'd wanted to stop her, I would have crated her at night.
She did learn "leave it". That training is done on-leash.
Puppies tend to grow out of chewing. None of my sight hounds liked to chew on hard items, and that might be some of your issue. The pup needs to chew, but needs something soft to chew on.