It's not about the undecided. You'd have to have brain worms to be undecided when Trump is an option. Undecided right now is like choosing between a stale pile of dog shit and fast food and justifying it by saying "well fast food is pretty shitty".
It's about getting people to VOTE. People who don't usually vote need to get out and vote. That's it. That's what's going to make the difference. Kamala has to mobilise reluctant voters.
It's not about the people who are undecided between Kamala and Trump. It's about the people who are undecided between Kamala and not voting at all.