accessToken

OAuth access token, for calling Google APIs on the user's behalf. Availability differs by platform: iOS, desktop, JS and wasm always return one; on Android, Credential Manager returns an ID token only, so a token is fetched through a separate authorization request (with its own consent prompt) when requestAccessToken = true or when scopes beyond email/profile are requested. The legacy Android fallback, used when Credential Manager is unavailable, never returns one.