As per Apple Docs
Importing Objective-C into Swift
To import a set of Objective-C files in the same framework target as
your Swift code, you’ll need to import those files into the
Objective-C umbrella header for the framework.
To import Objective-C code into Swift from the same framework
Under Build Settings, in Packaging, make sure the Defines Module
setting for that framework target is set to “Yes”. In your umbrella
header file, import every Objective-C header you want to expose to
Swift. For example:
#import <XYZ/XYZCustomCell.h>
#import <XYZ/XYZCustomView.h>
#import <XYZ/XYZCustomViewController.h>
So, officially, it looks like there's no way to see an Objective-C class in Swift files without exposing it publicly. ☹️