Best way to pass parameter while using RxJS forkJoin

So, I have a service that has three functions that I need to execute.

I use forkJoin because I want to take further action when a response has been received for all! One of them needs to receive one parameter.

getDevices(id: string): Observable<IEquipmentRow[]> {
    const url = `${apiUrl}/${id}`;
    return this.http.get<IGetDevicesResponse>(url)
      .pipe(
        map(res => {
          return res.data;
        })
      );
}

private regions$ = this.getRegions();
private devices$ = this.getDevices();


public equipmentPreparationData$ = forkJoin({
    regions: this.regions$,
    devices: this.devices$
});

What is the best way to implement that? Maybe using RxJS Subject/BehaviorSubject? What about RxJS switchMap, can we use it here? I am new with RxJS, so be gentle :)

Try with:

// Change your response type
public equipmentPreparationData$(deviceID: string): Observable<any> {
 return forkJoin({
    regions: this.regions$,
    devices: this.getDevices(deviceID)
});


private getDevices(id: string): Observable<IEquipmentRow[]> {
    const url = `${apiUrl}/${id}`;
    return this.http.get<IGetDevicesResponse>(url)
      .pipe(
        map(res => {
          return res.data;
        })
      );
}

private regions$ = this.getRegions();

In this way, you can use your function with the parameter and pass through getDevices method