How can I use the group prefix outside the closure in Laravel routes

The scenario I want to achieve is that I want to access the prefix $fragment outside the closure.

So this is what I want to achieve:

Route::group([
    'prefix' => '{fragment}',
    'namespace' => 'AppHttpControllers' . 'V' . '{fragment}',
    'middleware' => [
        'v' . '{fragment}' . '.myMiddleWare',
    ],
], function ($pathParam) {
    Route::get(
        'hello',
        function ($fragment) use ($pathParam) {
            return response()->json([$pathParam]);
        }
    );
});

I also thought of doing something like:

request()->getHost()

But it returns null.

So it is quite evident that the variable $fragment would be accessible inside the endpoint /hello but it is not accessible outside of it.

Any help would be highly appreciated.
Thanks!