Harris shadows Biden because there aren’t enough handlers to manage them separately. If the 25th Amendment option was being considered it is likely off the table now. As you suggest, Harris has failed her audition and comes across as less competent than Biden. Actually Biden may have outsmarted them by placing her in charge of the boarder crisis, knowing she would fail miserably. As for Pelosi? Can’t see the DS wanting her in the role, she is as dazed and confused as Joe.