I read the book over the weekend, and it has been a pleasant and joyful experience. I have tried Go on Raspberry Pis, which is not bad except for the garbage collector, and some Assembler, Forth and C on various other boards long time ago. I personally like the embedded book WAY more than the Rust book itself, it (the embedded book) is terse, sharp, focussed, straight to the point and full of light bulb moments. I'm thinking about spending $15 on a Discovery board
Anyway, excellent job, congratulations!