This is the biggest adjustment writers have to make, which is to write a draft and add things later. You could mark something like:

xx add statistics about this xx

And then later when you are editing, you add the statistics. The idea is to get the structure of your writing out, then you add what was missing later. There is the idea that the best writers are rewriters.

A Chromebook would work, so long as you disconnect the internet. Otherwise, what ends up happening is you'll get email pings or want to research something. Two hours later, you come back to the paragraph you started.

George R. R. Martin, the writer of Game of Thrones, for example, writes on an old computer running a DOS version of WordStar.

https://wikiofthrones.com/george-r-r-martin-uses-36-year-old-software-write-books