If you are using Business or Enterprise versions of G Suite, you will no doubt already be using Shared Drives functionality. Google has finally enabled the functionality whereby authorized users can share subfolders under the primary folders inside Shared Drives. 

To use this functionality make sure that you have "Manager" permissions for the base folder (Shared Drive's Drive) 

 Next right-click on the sub-folder you wish to share and choose "Get link"

In the dialog that pops up, change the permission at the bottom from "Restricted" to either your domain users or "Anyone with the link" and click Done.

Now only can you right click on the folder in question and choose "Share" as you would in regular Google Drive.

In the share popup, you can choose who you would like to share the folder with and if their permissions.