Saint Abanoub is a Child Martyr who was martyred in the year 304 A.D. and is a Saint of the Universal Undivided Church. Even though he is not currently in any calendar of any of the EO (Eastern Orthodox) Patriarchates this doesn’t matter as he was martyred for the Faith before any Schism. The Egyptian Church (the Patriarchate of Alexandria) venerated him before the schism at Chalcedon. So he was venerated by the Coptic Church (he still is to this day) before the Schism of 451 A.D., when they were still in communion with us.

He is, therefore, an Orthodox Saint. He should be venerated and prayed to. And iconographers should paint Byzantine icons of this powerful Saint! – Maxim https://orthodoxreflections.com/akathist-to-the-great-martyr-saint-abanoub-the-holy-child/