This never became a real language, but years ago Microsoft Research work on Project Midori, an attempt to make a managed programming language suitable for an operating, and the operating system to go with it. It was based off of C# and heavily modified. Joe Duffy at Microsoft Research wrote some good blogs on it, about approaches they took and why, problems they ran in to, etc.
another option is to have an epub version of it that you can load into a reader. you should be able to add bookmarks etc. It might not be as feature-rich as an app, but if you want privacy, it’s about as close to reading a book as you’re going to get.