Parse Arguments from URL for Flutter Web App

My Use Case:

Users in my app can create lists of items. I want the users to be able to share a link to one of their lists.

I want individuals who click the shared link to see the list of items in a web browser and not need the app installed.

I originally thought Dynamic linking was what I was looking for. But as I have done more research I don't think I need dynamic linking to just read info from a link and the navigate to the right view in the web app.

My Attempt: onGenerateRoute

Doing some research I stumbled onto this Stack Overflow Question: How can a named route have URL parameters in flutter web?

After reading that I tried this in my own code:

routes: appRoutes,
        onGenerateRoute: (settings) {
          if (settings.name == "/pack") {
            //in your example: settings.name = "/post?id=123"

            final settingsUri = Uri.parse(settings.name!);
            //settingsUri.queryParameters is a map of all the query keys and values
            final postID = settingsUri.queryParameters['id'];
            print(postID); 

            Navigator.pushNamed(context, '/home');
          }
        },

I wanted to see if I could just print the id passed in https://myApp.app/pack?id=100

Unfortunately, I can't even get to that point to test my code above. I depleted my web app to my domain and if I go to any address other than https://myApp.app then I get a 404 error. Anything after the main URL like https://myApp.app/anything will go to a 404.

I have a hunch I need to edit my firebase.json. Right now it's set up for dynamic linking with /p but not sure what I need to fix here or someplace else to have the above code execute and not route to a 404 error page.

firebase.json

{
  "hosting": {
    "public": "build/web",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "appAssociation": "AUTO",
    "rewrites": [
      {
        "source": "/p/**",
        "dynamicLinks": true
      }
    ]
  }
}