Is it permissible to work in a supermarket in America that sells foods containing pork, knowing the difficulty of finding another job due to the lack of official documents? And is eating for free from the store with the manager's approval, despite company regulations that require payment with a discount, considered unlawful (haram)?

It is not permissible to work in a place that sells food containing pork. It is also not permissible to eat food from the establishment without paying for it if the company prohibits it, even if the manager gives permission, because he does not own the food. The Prophet, peace and blessings be upon him, said: "The wealth of a person is not lawful except with his good consent."