They're all okay to give, though nuts are fatty like cypher said, so feed sparingly!
Sisal string is also perfectly safe to use, and is better than most available
here's a list of some safe nuts and seeds.
"Pine nuts
Quinoa
Peanuts (monkey nuts)
Walnuts
Sweet almonds (deshelled; NOT bitter)
Brazil nuts
Beech nuts
Millet
Hazelnuts
Pecans
Pistachios
Cashews
Flax seeds (excellent for coat health!)
Chia seeds
Sunflower seeds
Pumpkin seeds
Sesame seeds
Chestnuts
Niger seeds"
If you have any other questions, please ask!