Is there a way to generate the coverage report from
flutter drive --target=test_driver/file.dart
??
No, it is not currently possible, and probably never will be:
https://github.com/flutter/flutter/issues/7474.
Furthermore, the Flutter team is moving away from flutter_driver in favor of augmenting flutter_test to work on devices, because flutter_driver is hard to embed in CI toolchains. As a result, many flutter developers opt to use Widget tests instead (which do support coverage, to be sure).