I couldn't find any mention of the Inertiajs package with vuex, maybe I am misunderstanding the Inertiajs concept? How do I use the Store in Inertiajs?
It is entirely valid to use Vuex with Inertia. It was stated multiple times by the creator itself that some tasks are better achieved using standard XHR requests. So if you need Vuex to prep some data and do some standalone API calls, go for it. As for the implementation, it is the exact same as for any Vue project (from what I can understand, it is something you have done in the past).