Really like this thing Walz does when they're appearing side by side -- he points at Harris or gestures at her in some way like "hey! Look at her! Here she is, the star of the show!"
He's doing for her what Biden did for Obama: an old white guy being visibly happy to play the part of the #2/sidekick/hype man for the younger person of color. (I know that Walz and Harris are technically the same age, but yknow.) In her case, he's also showing that it's cool for a guy to be there to support a woman, and for her to be the undisputed boss. All of which are great qualities in a VP.