It depends on the quality of…
It depends on the quality of the stainless steel. Removing iron during the smelting process is time consuming and expensive. My 30 year old stainless Kenmore range hood is cheap. Magnets stick to it. So iron is present. The tea kettle I boil water in is real stainless. So magnets do not stick to it. If I were to consider buying a Cybertruck (I would not. They are the ugliest vehicle on the road since the Pontiac Aztek.) I'd bring a small magnet and challenge the dealer to see if it sticks to the body panels.