It was My Emoji Maker app. In other words: The My Emoji Maker app allows users to turn themselves into animated emojis that they can then share in messages or social media (via Reddit 1, Reddit 2). Indeed, the same function that we know from the Galaxy S9 and Galaxy Note 9.
The My Emoji Maker app is available on Samsung’s Galaxy Apps store. According to the description on Galaxy Apps, the app is for use with the My Emoji function within the camera.
According to the Reddit post, the option to “Create My Emoji” can be found by clicking on “Stickers” within the device’s camera app, just like the Galaxy S9 smartphones. However, it is currently not possible to open the app for most users.
If you have a Galaxy S8/S8+ or Galaxy Note 8 and you want to download My Emoji Maker, you can do so by following this link to the Galaxy Apps store.