I believe it’s possible to both feel easy AND be highly effective. Extensive reading would fall in this quadrant. Trouble is that below a certain level you nee

I believe it’s possible to both feel easy AND be highly effective. Extensive reading would fall in this quadrant. Trouble is that below a certain level you need lots and lots of graded readers. A somewhat improved version of OP’s project may solve that problem, providing an unlimited firehose of reading at an appropriate level.