Store

const store = ({
  // Create a state with the reactive function we imported previously, this will manage the reactivity for us
  state: reactive({
    count: null 
    // If this is null is for the example,
    // of course you can initialize the
    // counter with 0 directly
  }),
  // This section will handle the getters
  getters: {
    getCount() {
      return store.state.count
    }
  },
  // This section will manage the changes into the state
  mutations: {
    incrementCount() {
      store.state.count++
    }
  },
  // This section will manage the actions needed for our store
  actions: {
    initializeCount() {
      store.state.count = 0
    }
  }
})

Vue 3 custom store
Ref: https://dev.to/manuelojeda/learn-to-create-your-custom-global-state-management-with-vue-3-11am