I'm exploring ways to limit exposure to lead (lead dust) when tumbling. One suggestion I got from a post on another board was to wash and dry the brass before tumbling.
So yeh, people wash brass with soap and water and it does not harm the cases.
I'm not enamored with super shinny brass. Brass does not need to be new looking to perform perfectly. In fact, I like using nickel plated brass but it is not easy to find during the shortage.
If you washed your brass in soap and water and it is clean there is no need to do anything else. Before you reload with powder, make sure the cases are completely dry.
I would NOT use a food container to wash brass. Use a plastic tub that will not be used for food. Wash your hands frequently to get rid of any lead.