He is non-tech-savvy and has been running this site for 20+ years. It used to be entirely plain HTML and he was on one of those $20/mo web hosts for 15 years and just FTP'ing HTML files to update it.
A few years ago I helped convert his content to Markdown in hopes to future-proof it a bit, and picked a simple Markdown file-based CMS (PicoCMS) to run it, and he has been happy with it. He has been able to publish more content, more regularly, because of its ease of use (web GUI) and not having to write HTML, FTP files, etc.
This is hosted on a $5/mo box on one of the newer VPS providers.
I was wondering if he wanted to move to using something like Netlify and GH Pages and take advantage of fully free hosting, what would be a good option for content editing? I'm aware of engines like Hugo or a number of others (like those listed on StaticGen) but for content-editing they pretty much come down to editing Markdown files and committing them into a Git repo. I fear that understanding Git workflows and how Git works in general is too much to ask of a non-tech-savvy writer. The Github.com UI might be fine but generally it's too code-centric and too many features on the UI for someone who just wants to edit/create new markdown files in folders.
Is there some open source library that provides a nice web GUI that allows for CRUD in a Git repo, that abstracts away everything about Git workflows, and just let you save files like on a harddrive? There is no need for multi-user in this, he is the only person who edit/updates files on the site.