Any modern keyboard will be able to insert emojis for you, so there isn't really a reason to build this directly into Pulse SMS.
If your keyboard doesn't seem to support emojis, then we recommend checking out Google's Gboard Keyboard. It works great and will allow you to insert emojis anywhere, not just on the Pulse SMS app.
Pulse SMS also allows you to change the look of emojis in the app. If you go to Settings > Emoji Style, you can choose between your system's default emojis, Google Android emojis, among others.