sharepoint online – Discussion board/comment exchange around individual document in document library

I want to have a discussion functionality around each document stored in the SharePoint Online document library.
Users can exchange comments around each document and can see the interaction. It is similar to Discussion Board APP but the only difference is that the discussion needs to be around a single document. As with the discussion Board APP, too many discussions around different documents can confuse the users.
Could you please suggest any OOTB functionality or any other easy-to-implement idea?
Thank you very much for your support.