Interests: Regular Expressions, Linux CLI one-liners, Scripting Languages and Vim
Check out https://github.com/auctors/free-lunch (list of free Windows software)
See also https://www.nirsoft.net/ (freeware, not open source)
GVim.
Check out https://ghostwriter.kde.org/ if you are looking for a GUI app with live preview, full screen mode, etc.
Check out https://novelwriter.io/
I’m not familiar with such softwares (I use pandoc for technical writing), but might help you…