Me too was thinking about how to create cloze or Q&A type flashcards inline using the same approach of sticky ToDos and collect them for review in a central repository or deck.
I saw a similar approach here using dynaannotate. This was created by @Sii I guess. See this video. https://m.imgur.com/zzgCtEk
Thats when I started thinking about the possiblity of using dynaannotate to create sticky todos. Not sure whether its doable or not.
@Mark_S has also done some work on dynaannotate. May be he can give some insights regarding this.