Is it permissible for my husband to sell materials abandoned by a government entity he used to work for and from which he personally benefited? Am I obligated to inform the purchasing party of their source? And is it permissible for him to sell materials his partner purchased that remained stuck at the airport and keep all the profit for himself?

If those responsible for the aforementioned materials renounce them out of disinterest, then there is no blame upon the husband for taking them, because they are permissible, and whoever precedes to a permissible thing has more right to it. He is not required to inform the buyer of their source. As for what has not ceased to be owned, it is not permissible to take it except with the permission of its owners, and the wife should denounce that to him. As for the goods shared between the husband and his partner, the partner's failure to bring them in does not remove his ownership of them, and the husband is not allowed to sell them individually without his partner.