How to map observable object with inner observables?

How to map observable object with inner observables?

Following is how I fetch details of an item. I want to map the received object with a property unwrapped.

              this.fetchData.getItemData().pipe(
                mergeMap((item: any) => {
                    return {
                        ...item,
                        images: item.images.map(id => this.http.get(baseUrl + link)) -->> I want to unwrap here. (it is an observable; that's why!)
                    }
                })
              )

Here I'm mapping the inner property images which is an array to an array of observables!!!

This is what I've tried:

              this.fetchData.getItemData().pipe(
                forkJoin((item: any) => {
                    return {
                        ...item,
                        images: item.images.map(id => this.http.get(baseUrl + link)) 
                    }
                })
              )


              this.fetchData.getItemData().pipe(
                mergeMap((item: any) => {
                    return {
                      ...item,
                      images: item.images.map((id) =>
                        flatMap(() => this.http.get(baseUrl + link))
                      ),
                    };
                })
              )

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