I had never heard of Pinia. Visited their landing page [1] and there's a button selling a course on how to use the library. There's a CTA for the course when you go to the Guide page as well. Very strange!

1. https://pinia.vuejs.org

In 2018, I taught Vue workshops where I memorized a Vue enabled html page and went through links from the homepage. Since then, Vue took permutations of options/composition, js/ts, Vite/whatever and deferred documentation to Vue teaching sponsors.

Try it. No course needed. Whatever you learn in the first hour scales to the 100th hour.

That's the best kind of simple.