My passport was speedier than I expected:
10/13/2021: Applied for expedited adult first US passport. I just went to the post office
10/14/2021: US DOS received passport application
10/18/2021: Application status changed to ‘In Process’
11/07/2021: Application status changed to ‘Approved’ with USPS priority express mail tracking number included, and estimated delivery date of on or around 11/10/2021
11/08/2021: USPS says it is out for delivery
Assuming it arrives with the mail later today, 21 days door-to-door.