Yes they do. Google Pay or Google Earth are using Flutter. They also contribute to Kotlin Multiplatform and use it for Google Workspace (gmail, drive, etc)
Flutter and Kotlin Multiplatform are two different frameworks. Flutter is mainly for cross platform UI. KM is mainly for common-core (or common business logic). My point still stands that these are all bloated and ugly.
Google products are an absolute mess. They create android, KM, and Flutter for mobile development. They also created MLKit, MediaPipe, and TensorFlow for AI. They're all over the place with their solutions