Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
Interestingly enough, while the Coptic Church has a Liturgy to Saint Gregory the Theologian, the Ethiopian Church has our own Saint Gregory liturgy, however it is to Saint Gregory of Nyssa, brother of Saint Basil. I wonder the disconnect between Alexandria and Ethiopia, generally speaking we share their literature and prayers, and anything we have that they don't is either an indigenous Ethiopian original or a copy of a foreign text which the Ethiopians themselves translated but which were lost outside of Ethiopia (such as with the Book of Enoch and Jubilees which are still faithfully in the Ethiopian Biblical Canon). We also have a Liturgy of Saint Gregory the Wonderworker.
stay blessed,
habte selassie