I was under the same impression as well. I have been using https://docusaurus.io/ for some time now and I am very happy with it and I am pretty sure there are other tools out there as well.
What sold me on Znai was the integration of code snippets (straight from source files, mining them out of the code) and integration of diagramming from PlantUML, which is done in a way that is compatible with the format used in Gitlab, VSCode and other markdown renderers.
Markdown has turned into a truly amazing ecosystem.
[1] https://testingisdocumenting.org/znai/introduction/what-is-t...
Is it a lot to set up or is it just markdown all the way and works out of the box?