Personally I found the demo kind of cringe - why the drake meme? Computers do not "struggle with too many digits" why use a metaphor that's just wrong?
With the "1 to 2 Machine" Demo the only feedback you get on no action is "green box is looking a bit empty." Not engaging really.
I think this would be useful for a motivated kid, but in that case Khan Academy already has way more content and is free. Don't see why you'd pay $50/month. That's to say nothing of YouTube which has even more content than Khan Academy, and is again free (or $15 if you don't want the ads).
Finally, I don't really see the "AI" here. The demo as constructed is basically a Google Slide deck with some JavaScript sprinkled in. A true "AI" experience would be that you, at any moment can ask for help and contextually it would help you. So in the case I described earlier it might go back and redisplay with arrows, or perhaps make the colors even more obvious.
Good content is obviously important, but there are literally millions of teachers redundantly creating content every year. It's easy enough to create canonical good content, no AI needed.
I imagine this will be completely ineffective or even counterproductive to an unmotivated, poorly behaved child.