Apologies if this doesn't count as a good source, but Italian Holocaust survivor Primo Levi describes being allowed to work as an assistant in a factory making synthetic rubber in his book If This Is A Man due to his experience as a chemist. This would seem to indicate that highly educated Jewish Holocaust victims would be allowed to work as skilled labor under certain circumstances.

Jewellers were given jobs outside of the ghettos sorting out/extracting gold and other precious metals from material gathered from concentration camps. It's discussed vividly in Schindler's Ark, which also talks more broadly about how jews in poland were employed at that time by Nazis.