Smoke!

[Imp]

I think for WWII infantry smoke use may be a bit over the top but not done major research.
US for sure used it, Brits & Germans to a lesser extent. Rest probably hardly used apart from maybe engineers, storm troopers & the like.
USA & perhaps Brits from 44 were possibly the only sides with regular availability.
However game does not really take that into account, most late German artillery should only have a few shells available due to shortages for example.