As with many Large Language Model projects, much of the difficulty is in prompt engineering in order to supply a consistent user experience. In this case, I want the model to be creative and flexible, but it's also very important to keep the content age appropriate for children. Less critical but also important for the user experience is to have the AI write at the correct level. Tuning the langugae and API parameters to result in a good product experience took many tries.
Additionally, this was the first time that I build a web app from scratch, by myself, handling the entire stack. There was a learning curve at the beginning picking up new prototyping tools. In building something from scratch, I also got to make my own tradeoffs in moving quickly and trying to get the product out the door, while also building in a way that was extensible and maintainable.
I built this project from scratch, including user research, application architecture, front end design, backend design, and implementation. Also the branding, marketing, customer support, etc.