I don't think it would have made a difference and from what staffers have been saying, Harris' internal polling never had her really in the race at all. This election was lost when Biden decided to try and run again and didn't allow for a regular primary process. She was never able to make up the polling difference (which, once again shows that public polling has all the validity of preseason college football polls).
However, not going on Joe Rogan was a critical error, and really the only preventable mistake she made. She was clearly trying to reach those voters during the campaign (and now hearing about their internal polling it becomes clear why as they wanted to take away Trump voters and really try to close the gap). Whoever those two people were should never work in politics again. It was an opportunity for 3 hours with the people she was trying to court and it not being filtered through the right wing media that they usually only hear about her with. If there is a lesson from her campaign that is kept, that is the one that needs to be a take away. Go to where the people you are trying to convince to vote for you are. Trump did this and it paid off for him.
The Biden stuff was not her fault and she ultimately couldn't control that so I don't hold her responsible for that.