Once you learn about APIs as you have just done, you realize that there is a world of possibilities of what you can build. Your own startup? Your own app? The possibilities are endless. Here is my favourite resource listing some of the public APIs you can use to build anything you want. Enjoy exploring it!

https://public-apis.xyz

Finally, an important skill to develop is the ability to read documentation of an API and learn how to use it. Try playing this game, read the documentation, and use the developer tools to "debug". It will be good practice and a lot of fun! https://play.elevatorsaga.com/