Quantifying any of those values would be completely pointless.
If you really want to know, "officially" a pinch of salt is ~0.35g and a dash is ~0.7g. Accurately measuring quantities that small is a trained skill using specialized equipment. Anything you can buy on Amazon for under $1,000 would get you +-100mg when used correctly at best - used in a kitchen with a 50g measuring spoon for 0.5g of salt you'd be lucky to get +- 1000 mg.