I have never gotten in to the nitty-gritty of what Netlify can do but the free tier is my go-to tool for posting fun little side projects.

Buy a domain, create a new site linked to a Github repo, and write HTML and push!

(Not a paid shill, just a happy user)

But to the question asker's original point

> what's the easiest way to sync a TXT file onto the web?

For my personal website I use a custom static site generator and rsync

> rsync -a output_folder/ website_host:/var/www/website_folder --delete;

where "website_host" is an alias in my SSH config file.

> [...] all of them require multiple manual steps and feel complex

I create a bash script called "publish.sh" in every project so I don't have to remember these things.