Making Http requests using Angular routing?

I think you don't need fake http requests do to that. As you said you have a service layer, so you may storage the sever result at moment you made the first request to the endpoint. Some ideas here:

1 - ShareReplay: where you keep the request for the subscribers doc

2 - Storage: Save the request data at client storage (like localstorage or something else)

  listUsers(): Observable<User[]>{

    const storageUsers = localStorage.getItem('users');

    return storageUsers 
    ? of<User[]>(storageUsers) 
    : this.http.get<User[]>(`some-end-point/users`)
       .pipe(
         tap(users => localStorage.setItem('users', users))
       );      
  }

3- Redux Doc

The router is used for displaying components given the location in the browser address bar. There are a few ways you can store past requests, but a service could be sufficient for your use case.

Given the information you shared, I've made some assumptions about your API usage and the StackBlitz I'm sharing would need more work to be a complete solution, but you can have a look at a dynamic "caching" service here: https://stackblitz.com/edit/angular-vhijkx

I've used a map to store responses for past requests, but you can use individual variables as well, given the use case. To persist the "cache" past a page load, it can be stringified and placed in localStorage or sessionStorage as well.

private cache: Map<string,any[]> = new Map();

getRequest(endpoint: string, termQuery: string): Observable<any> {
  const url = `${this.apiBase}/${endpoint}`,
    params = new HttpParams().set(this.term, termQuery),
    storeId = `${endpoint}:${termQuery}`,
    cache = this.cache.get(storeId);

  if (cache) {
    console.log('fetched from cache');
    return of(cache);
  } else {
    console.log('fetched from API');
    return this.http.get(url, {params}).pipe(
      tap(response => {
        this.cache.set(storeId,response);
      })
    );
  }
}

This method first checks if a cached entry already exist. If so, it returns an Observable thereof instantly, otherwise it does the API request and when the response is received, the cache is set and the Observable returned.