module map file '/Users/"my_flutter_project_path"/ios/Pods/Headers/Private/openssl_grpc/BoringSSL-GRPC.modulemap' not found?
The CocoaPods 1.9.0, the capability to specify dynamic/static linkage for each pod in the Podfile should get it better. It introduced the use of use_frameworks! :linkage => :static which is an even better approach than use_modular_headers!.