Harry and Fionn for People Magazine:
http://people.com/movies/harry-styles-dunkirk/ (video + written interview)
picture:

Interview with Harry and Fionn: https://vimeo.com/226188938

Despite what the title suggests, some of the other cast members and Nolan also speak in this interview.

better quality video of the Today Show:

Harry and Fionn on the Today Show
https://vimeo.com/226144220 (5 minute video)
and a picture:

Harry, Chris, and Kenneth:

more Harry and Mark https://68.media.tumblr.com/cf208ccae960572bb774f3e3a969915b/tumblr_otbh21X4iW1rnntmfo2_540.png https://68.media.tumblr.com/7d0c7848b25fb5ceb384f0dc605fe17b/tumblr_otbhdqSfoz1ugbj9yo3_540.png https://68.media.tumblr.com/6c620a1853e706eb7af532133fbb91e7/tumblr_otbh78pj0P1rnntmfo1_...

Harry & James D'Arcy Harry & Kenneth Branagh