Who was Abram Hannibal in Aleksandr Pushkin’s family history?

Abram Hannibal was the maternal great-grandfather of the Russian author Aleksandr Pushkin.1

According to family tradition, Hannibal was an Abyssinian princeling who was purchased as a slave in Constantinople and subsequently adopted by Peter the Great. He eventually became a comrade-in-arms to the tsar. Pushkin later immortalized his ancestor in his unfinished historical novel, Arap Petra Velikogo (The Negro of Peter the Great).1

Please note that this Abram Hannibal is a distinct historical figure from the famous Carthaginian general Hannibal, who is known for his military campaigns against Rome.2