Is it permissible for a person to dedicate the reward of their glorifications (tasbihat) and remembrances (adhkar) to those whom they have wronged, as an expiation for the injustices and in preparation for the retribution on the Day of Resurrection?

The expiation for backbiting is to seek forgiveness for the one you backbit, to supplicate for their well-being, and to mention them in a good light whenever possible. If this is done, it is hoped that Allah will forgive and overlook the sin, and compensate the wronged person with good in the Hereafter. As for donating the reward of acts of worship to the wronged person, if they are deceased, there is no harm in it. However, if they are alive, the preferred view is that it is not permissible, but there is no harm in following the opinion of those who deem it permissible.