Can't initialize stores

[ejerskov]

Nuxt 3.14.1592 with @pinia/nuxt 0.9.0.

In my app, I need to initialize the useSettingsStore SSR because I need some settings before loading the app.
I have tried various ways to do this, some working locally, but all failing on production (Vercel)

From what I can read I should be enough to just add '@pinia/nuxt', to modules in nuxt.config.ts.
But when I call a store from App.vue I get an error:

<script setup lang="ts">
import { useSettingsStore } from '~/stores/settingsStore'
const settingsStore = await useSettingsStore()
if (!settingsStore.settings) {
  await settingsStore.fetchSettings()
}
</script>

Error:

[🍍]: "getActivePinia()" was called but there was no active Pinia. Are you trying to use a store before calling "app.use(pinia)"? See https://pinia.vuejs.org/core-concepts/outside-component-usage.html for help. This will fail in production.

I then tried to add this to Vue.app:

const pinia = createPinia()
useNuxtApp().vueApp.use(pinia)

.. and now its working locally.
But on production, I then get this error:
Cannot set property $pinia of #<Object> which has only a getter

I also tried to move this logic to a plugin, but it gives the same errors.

How do I initialize the stores correctly?