Rest assured that I haven't given up on the textbook / tutorial approach just yet, but I might have to "invent" my own publication technology to get the "book" that I want.
I find Jupyter notebooks in Python and Wolfram's Mathematica to be nearly perfect for explaining complicated content where you can easily format text, images, and inline code snippets.
github.com/rikedyp/learnapl
It is currently very rough around the eges and also in the middle. Work will continue in the new year.
There is also now a set of introductory problem sets that have been used in a couple of schools on problems.tryapl.org