Persistent top level layouts that use page specific info

[agstover]

TLDR: Is there any way to dynamically build paths and get StaticProps at the _app level? I want to 1) Build Entire tree of NavData from filesystem and 2) Manage which data is fed to the Nav based on dynamic route.

I'm trying to build a site similar to the Stripe Docs, and I want both the header with its MainNav and the SidebarNav to be a lop level component defined in a Layout component so I can have persistence of the Navigation between pages.

I'm using a getLayout function attached as a static property to each page to handle this as suggested in this blog post by TailwindJS creator.

Example:

// pages/resources.js
const { withLayout } = require("../components/layouts")

export default function Resources() {
    return (
        <h1>RESOURCES</h1>
    )
}

Resources.getLayout = page => withLayout(page)

// pages/_app.js
import '../styles/index.css'
import { AnimatePresence } from 'framer-motion';

function MyApp({ Component, pageProps, router }) {
  const getLayout = Component.getLayout || (page => page)
  return (
    <AnimatePresence exitBeforeEnter>
      {
        getLayout(<Component {...pageProps} key={router.route}/>)
      }
    </AnimatePresence>
  )
}

export default MyApp

What I would like to do and am unsure how to do, is I would like to build the Sidebar navigation off of the filesystem. For example if I have a Subjects folder with "physics", "math", "chemistry" content directories, I would like the SideNav at build time to look and automatically build navigation values off of these file systems, that way I can add some later and they will automatically be included in the navigation. If _app had a getStaticProps function this would be easy, but that doesn't seem to exist yet.

Also, I want to change the visible SideNav values based on the route. So if it's 'learn/physics' then the physics nav data will be fed to SideNav. However, I'm using the [...subjects].js static page pattern, and when I navigate to a page like 'learn/physics', Next router feeds me 'learn/[...subject]' as the path.

Is there any way to dynamically build paths and get StaticProps at the _app level? Or do I have to push all of this work of managine the SideNav and its data down to the page level and lose page to page persistence of having a top level component?