If you pick them before the peas have had time to mature the pod may be edible, but wont taste like a sugar snap pea. Yes you can grow your peas in a grow bag with bamboo canes though a large container might be easier.

Not a suitable crop to grow in a bag as you won't get more than one picking for your dinner, best to grow in a shallow trench in the garden supported by twigs or pea netting.