exactly, even for a single person maintaining just a few pages with a bit of style and navigation is already a chore. i'd rather use a js framework or even xslt than edit the menu on every page, every time i need to add a new page.

With jinja you’d use template inheritance and just update the base template for this:

https://jinja.palletsprojects.com/en/stable/templates/#templ...

sure, that's just one of the many frameworks or tools i could use. the point is, there is no way to do that without any processing, either on the server or in the browser.