Revision app recommended features

im making a revision app rn and im looking for feature recommendations i currently have

• Flashcards
• Flashcard Heatmap
• Notes
• Mind Map
• Scientific Calculator
• Graphs (like desmos)
• Timer
• To‑Do List
• Revision Timetable
• Countdowns
• Activity Calendar
• Progress Tracker (mocks + flashcard accuracy)
• also ai helper feature (can be used offline)

you can import and export any notes or flash cards aswell. it can be for any level of education and im gonna make it be multi language. i need to fix the minor bugs and make the sign up/login page and all that and convert it to a mobile version and ipad version

any recommendations would be good