Yes. You're absolutely right.
I should make it clear that Github Pages also supports vanilla HTML.
But, if you're using Markdown or org files, you'll have to export your content to HTML in your machine.
For Hugo, for example, you will need to install go, hugo, all its dependencies and always remember to manually type an extra command to turn your posts to HTML. Remember that you'll have to do this for ANY modification that you'd wish to do.
For the automatic generation, at least the last time I used, Github Pages only supported Jekyll.