Geezime tigrigna keyboard app works today almost in every Operating system. To come to your point it also can work in MAC OS. For further information please can you write directly to the developer of that Tigrigna App their email address is this "email@example.com".
I would like to show you how, but it would request you money around 20 dollar. Let me know if you satisfy by my answer. I am happy you want to use it, because it is easy to use.