These are the first steps, the initial commands and the index.html file you need to start developing your Ionic App with Firebase.
Wordpress is system with a rich ecosystem of plugins. There is a plugin for anything you can imagine, some of them have a cost but most of them are free. Here is my personal list of plugins I used in the last blogs I've built with Wordpress. All of them are FREE and some of theme have a paid version but are fully functional in the free version.