I've been trying to find a solution to this exact problem. I use Notion as my PKMS and I've been struggling to find an integration to make flashcards with my content in Notion. Going to try out your system - thanks for sharing!

As an aside, Notion would completely disrupt the flashcard app space (Quizlet, etc) if it had a feature to create flashcards from a Notion database with spaced repetition. I really don't think it would be that difficult for them to implement that feature. Hopefully they will soon.