Well, that didn’t work.
I discovered that the WordPress.com desktop app requires an internet connection to run.
Let me re-iterate: I will be travelling WITHOUT INTERNET ACCESS for several weeks at a time. I would like to compose blog posts while OFFLINE, and then upload them to by site when I get access to wifi, which will only happen every few weeks.
I am not the only one travelling to areas without internet access. I am sure there must be a solution out there somewhere. I could go back to a page-based theme, but the way things are going (to block based editing) that would only be a temporary solution.