Incremental authorization with Firebase and GoogleAuthProvider - firebase

Question

I'm using Firebase v8 with the GoogleAuthProvider.
Firebase documentation provides the following code to authenticate the user.
firebase.auth().signInWithPopup(provider).then((result) => {
/** #type {firebase.auth.OAuthCredential} */
var credential = result.credential;
// This gives you a Google Access Token. You can use it to access the Google API.
var token = credential.accessToken;
// The signed-in user info.
var user = result.user;
// ...
})
Questions
Google's Using OAuth 2.0 to Access Google APIs article recommends incremental authorization (it's not Firebase, but the recommendation is clear)
It is generally a best practice to request scopes incrementally, at
the time access is required, rather than up front. For example, an app
that wants to support saving an event to a calendar should not request
Google Calendar access until the user presses the "Add to Calendar"
button.
AFAICT, there is no way to achieve incremental authorization with Firebase without re-authenticating the user. While scopes can be added to GoogleAuthProvider using addScope, a subsequent call to signInWithPopup is required (i.e. the user is re-authenticated). Is there any way to prompt only for authorization (e.g. Drive access) without re-authenticating?
Assuming the access token is short lived, can the Google ID token be used to obtain a new access token? Is re-authenticating the user the only way to obtain a new access token?
Is there a way to determine whether the access token has expired?