How we can access store instance in setup store

[cibilex]

I defined 'router' external property via plugin feature but I could't access it in setup store.

import { markRaw } from 'vue'
import { router } from './router'

pinia.use(({ store }) => {
  store.router = markRaw(router)
})

when we use option store is easy to access router via 'this' but in setup store 'this' is happening undefined.
I looked pinia documantation but I did not found anything about this problem.
Could somebody help me please.