What I was wondering about from the beginning: How many real Nim experts are in your group, and which advanced Nim projects have your group created already? I don't think that only Araq or Mratsim will be able to write a real Nim textbook, but I think that there are only a few candidates who may be able, maybe Mr Behrends or Mr Felsing, but both are not very active in Nim land currently. There may be some more known from IRC, maybe Mr Munch and a few other without real names. Others may be able to write tutorials or make videos for kids, but we have a lot of them already.
For your formal process: Why write in Latex still? Latex may be still a good choise when writing a book about quantum mechanics. But there is not much formula in a book about a programming language. And PDF should be not the prefered output format in these times. You do not really intent to sell a paper book? Or to sell a book at all? So HTML and EPub should be the main formats. Maybe use AsciiDoctor, Dom and Miran uses it for their tutorials. Of course this my personal view only. And I have to admit that I wrote my physics thesis with LaTeX, and maybe I would indeed buy a good Nim book, but I am sure only very few would buy a copy.
