TiddlyWiki (https://tiddlywiki.com), which I think is amazing both in simplicity and flexibility, also offers export to static sites. There are two versions: either the wiki as a single html+js-file or on node.js, but export to static html exists in both. You can test it from the home page (https://tiddlywiki.com), just go to Tools in the sidebar -> Export all -> Static HTML. Amazingly simple.

Not mine, but a (nice) demo: https://www.mentalnodes.com/ and more advanced guide: https://nesslabs.com/tiddlywiki-static-website-generator