Why it would take Obama a whole additional week to finally endorse her is odd.
Not really odd, the DNC works through a whole cadre of selectors. After the primaries, the people who actually get to vote are the wealthy Democrat donors, they get half the vote, then at the convention do the actual voters (the people) get half of the votes through a group of representatives (Clinton, Pelosi, Newsom etc).
Typically everyone kind of follows what the voters say, but they don't have to, at all, which they didn't do in this case, as Biden was already "elected" in the primaries, so he should be the candidate that is nominated.
What the Pelosi's of this world opine about has nothing at all to do with how the candidates are nominated. The Obama's had hoped there would be sufficient resistance to the Pelosi/Biden camp to dark horse someone else (probably Michelle) at the convention, however as I said before, (now Jill and Hunter) Biden has 50 years worth of dead bodies in their closet, as do Clinton and Pelosi which grants significant pull in the party which someone like Obama cannot compete with. Had Biden not endorsed Kamala (as the Obama staff writers didn't want to do, as is evident from the first Biden letter), then Obama would have had a chance for a 4th and 5th term.