The only "gimmick" in Dunkirk was the way Nolan sanitized it to be PG-13. You see German shells hitting soldiers, but the explosions are rendered immaculately. It carries on the tradition of British war movies being suitable for family viewing because it's important for everyone to understand the sacrifices that were made. The same criticism can be leveled at Sam Mendes and 1917.
?? Dunkirk is imo the best one of his non-linear narratives, with 3 storylines intertwining: one taking place in the span of one week, one in one day and the last one (the plane) in one hour.
It was Dunkirk I was most referencing in my original comment. I found it a very disappointing film. Here's this important human story that the movie refuses to tell clearly, making the whole thing hit less than the sum of it's parts. 1917 was much more effective in its stylistic choices in my opinion.