With difficult Brexit implementation issues looming, Boris needs friends. You can be sure he is bending Biden’s ear on this matter during the G7. Will he succeed?
To a large extent, yes. Biden may have been an opponent of Brexit and an EU partisan in another life, but his primary objective is a united front against China. He needs to have the rest of the G7 reading from the same page. As a result, you can expect him to function as a mediator of sorts between the UK and the EU for the foreseeable future.