Use defineRoutes with non-nested-URL routes

[caprica]

I have route files similar to this:

customer.tsx                           data loader, no UI
customer._index.tsx                    index page redirects to first section
customer._sections.tsx                 common layout for sections, with outlet, _sections not part of URL
customer._sections.$section.tsx        section page
  (many more child routes under here)
customer.nav.tsx                       separate menu navigation layout

I want to use defineRoutes in vite.config.ts instead of that, and so far I only have this:

plugins: [
  remix({
    routes(defineRoutes) {
      return defineRoutes((route) => {
        route('customer', 'shared/customer.tsx', () => {
          route('', 'shared/customer-index.tsx', { index: true });
          route('nav', 'shared/customer-nav.tsx')
        })
      }
    }
  })
]

I don't know how to replicate the common "_sections" layout, crucially so "_sections" or "sections" does NOT appear in the URL.

The examples in the official docs don't mention this case.

Does anyone know how to do this, or could point me to a similar example?

And a quick follow-up, if I want to achieve the same effect as non-layout-nesting routes, I just don't add them as children?

[caprica]

I didn't realise you could use the same path value more than once in the route definitions, by doing this same path with different files, I can achieve what I was asking about in my question.

For example, you can do like:

route('', 'whatever/_index.tsx', { index: true })
route('', 'whatever/_sections.tsx', () => {
   // add child routes here
})