Edit: I have already seen this video Bring expression to your app with Genmoji. But it is still unclear to me how one can create a genmoji in code, and reuse it. I want to create an emoji specific to my custom keyboard. Can I create genmojis with images? Or anything else I can design/create on my own and use it as a genmoji?

It's called SF Arabic

What are your device's specs?