Your comments are always welcome and also always make me think more about what I've written. I agree with you: It would be good to select someone who can speak to younger voters--like Buttigieg. I hope you're right that his being gay would be a minor problem. It would be among younger voters, but possibly not among older undecideds, only some of whom would vote for him (I wonder how many undecideds there are).
I also agree with you that Newsom would be unlikely to accept. His route to the presidency may be easier if he stays governor of California.
About Mayor Pete: I wish I had met him, but it wasn't me. The story on Reddit was by Donald F. Zimmer, who did meet him.
We'll just have to wait for Harris to make her choice, after consulting with a large number of advisors, of course.