Is it permissible to ask a shaykh known for his karamat (miraculous graces) to supplicate to Allah with me for the fulfillment of a need, while having complete certainty that needs are only fulfilled by the will of Allah Almighty?

Seeking prayers from a righteous living person is permissible, as long as it does not lead to the one seeking the prayer or others being tempted (into error). However, this does not include traveling to a specific person to ask for their prayer, especially if that person is one who seeks help from jinn to know the unseen. In such a case, one should not ask for prayers from them; rather, one must be wary of them. A Muslim should strive to supplicate for themselves.