Slitherine

The wiki says that units can gain some traits from experience, but does not seem to give any details- is there a list with this information somewhere?

You likely mean medals, which are awards units get for doing specific things. See the Awards table here:

https://panzercorps.fandom.com/wiki/Heroes_and_awards

Note useful to know - Dependable Support traits can be gained by units as long as they have a way to trigger support fire (for example, if you assign an AT Support or Artillery Support hero to a unit that normally does not have a support fire option, it will start gaining the numbers towards the requirement with each support fire provided). Same for Steamroller and triggering overruns thanks to the Overrun hero. However, both medals stop working once you unassigned that hero from the unit. Also, fighter planes too gain Dependable Support, even if it does not get tracked on the unit card in the medals section.

Thank you!