Here are three interesting WW2 movies that as far as I know haven't been filmed yet.

1) the heroic doomed stand of the Commonwealth troops (including many Canadians) at Hong Kong December 1941 against Imperial Japan.

2) the deadly battles between tiny patrols of Americans hunting armed German meteorologists on the Greenland interior ice.

3) The Niihau incident, where a crashed Japanese pilot was imprisoned, then escaped, then terrorized the Hawaiian village until he got pummeled by a gigantic Hawaiian dude after shooting the Hawaiian multiple times.

Add your own candidates.