Scrivener explicitly targets non-fiction writers as well. There are template projects for essays, papers and proposals, with support for LaTeX as well as variou

Scrivener explicitly targets non-fiction writers as well. There are template projects for essays, papers and proposals, with support for LaTeX as well as various citation styles (I recall at least APA and MLA). The notes and research sections of the project are even more useful for non-fiction writing in my opinion. For programming books especially I recall Scrivener 3 added basic support for code blocks. No syntax highlighting, but if you export to HTML or LaTeX you can use a library or package for that.