Lacuna is a spaced repetition app that uses FSRS to schedule for the exam date, rather than indefinitely like Anki. Lacuna works around you - the scheduler can be used at all times, rather than just when the flashcard is due - which means that you can squeeze studying into the time that's convenient, without sacrificing quality It has easy importing from Anki and also all the features that you need. It's fully offline and private, with no data sent anywhere unless you choose the opt in sync.