[shrew]

I love no-JS type hacks and solutions as your post has suggested, but I would actually be more concerned about using solutions like your hidden menu in production than what the parent has suggested. Some of them, like the checkbox dark mode, are indeed hacks and cause issues with accessibility, and when I've tried a suitably complex burger menu without JS, I find it a buggy and annoying UX.

I think the true progressive enhancement route would be to render the menu either visibly on the page (maybe at the bottom?) or on a separate page entirely. Your burger menu icon is a link (either an anchor to bring the menu into view or to the dedicated menu page) and if JS is supported, you hijack the link using code similar to the parent comment and add a class to bring the menu element into view from there.

In doing so, your page can work just as HTML, not even CSS required, and if JS is supported then you have real state management to control the visibility of your menu (although accessibility concerns still potentially exist if you're not careful!).