Is repentance permissible after having given alms equivalent to the value of sand dumped for a government entity and the value of stones bought from someone other than their owner, given the impossibility of returning them to their original owners?

There is no objection to taking a bag that has been left behind because its owner no longer desires it, for it is permissible for whoever finds it first. This differs from building stones, for which one must search for their owner or heirs to return compensation to them or seek their forgiveness, due to the Prophet's (peace be upon him) saying: "On the hand is what it took until it returns it," and "Whoever has wronged someone, be it concerning his honor or anything else, should seek his forgiveness today." If it is impossible to reach them, the money should be given as charity on their behalf, with the intention that the reward goes to the original owner, as mentioned by An-Nawawi and Ibn Taymiyyah, who cited examples and stories supporting this.