Is there any way using the new Vue.js [Reactivity API](https://v3.vuejs.org/api/reactivity-api.html) to bind an object key to an existing Ref value as readonly?

**Example**.

```
setup() {
  const input = ref({
    firstName: 'Bob',
    email: 'bob@so.com'
  })

  const args = {
    postID: 32,
    email: readonly(input.value.email)
  }

  return { input, args }
}

```

This doesn't work.  

`args.email` doesn't get updated.