Hey there,
in Anki, there is a feature that allows you to draw something on a white notepad before checking the flashcard.
This allows practicing complex structural chemical formulas or other “drawing related things”.
Especially when studying medicine or sciences in general, I think this is an essential feature and should be part of the IOS app (therefore usable with Apple Pencil).
This is how it looks in Anki, though I am sure there is a more fashionable way to solve it 
I hope you can take my request into consideration.
Best regards, Tobi!