Pass query string to each route from Shopify to an embedded app?

Shopify Partner
6 2 0

I get it, we now need to use cookie-less authentication and that's fine. I made the changes in my Next.js app but my app is an SPA and since I'm using Next.js I want to take advantage of `getServerSideProps` to avoid displaying loading indicators where I don't expect the user to get one.

How do I get to pass the query string in each request to each route? I could use a `shopOrigin` cookie but then I won't have a way to verify the request is coming from the current shop.

Here's a more elaborated question with images: