Yes! You can convert your existing flashcards into Study Sets:
Import existing flashcards from other apps (like Anki or Quizlet) straight into Study Sets. Please refer to this how-to guide here.
Convert GoodNotes flashcards directly. Open your flashcards, tap the 3 dots in the menu, and select "Convert Flashcards to Study Sets"
Import new Study Sets from the following file formats: TXT, .CSV, or .TSV.