That is addressed in paragraph 2. At the start I needed to address problems with handwriting, which meant that the evaluation of whether he has done the flashcard correctly has to be done by me. Having flashcards on a computer, and then a manual evaluation, seemed like counterproductive complexity. I did not want a computer between me and my son for this activity.

But it turns out to be a good thing. Because the fact that I have been involved has let me track down issues, such as the need for a reward activity. Anki currently does not offer that as a feature.

However in a year or so I do want to move my son to something like Anki.

FWIW: I used Anki for learning a foreign language, with the help of a human, who would ask one side, and then rate my answer. This worked pretty well, in fact, and allowed the devolvement to Anki of spacing and scheduling, with the benefits you've mentioned.