Nice to see them attend church with the queen. I could imagine them perhaps having lunch with her after. Great that they spend some personal time not just the commonwealth event, with his grandmother.
From what I read this morning it seems they attended because there was a bit of a memorial service for a member of the military taking place and this soldier's father happened to work for the Queen at Windsor for a number of years. Admittedly I didn't read the article in depth because, well, no time for that when the office phone is ringing off the hook with questions about school closures due to coronavirus now hitting our state but it does seem as though they attended because Harry had some part in that service rather than just to spend time with HM.