To your second question, if Biden becomes president, then Trump’s cabinet will likely resign, and if they don’t then Biden will fire them. If the senate refuses to confirm Biden’s appointees, then the answer to “Who is the senate-confirmed X on Feb 15 or March 1?” is nobody, and therefor definitely not Mike Pompeo or Bill Barr.
To your second question, if Biden becomes president, then Trump’s cabinet will likely resign, and if they don’t then Biden will fire them. If the senate refuses to confirm Biden’s appointees, then the answer to “Who is the senate-confirmed X on Feb 15 or March 1?” is nobody, and therefor definitely not Mike Pompeo or Bill Barr.