This can be achieved by using forkJoin, this operator takes an array of observables and waits for all the source observables to complete. Once they all complete, it emits an array of the last emitted values from each observable. Example: 

import { forkJoin, of, throwError } from 'rxjs';

 const observables = [
     of(1,2,3).pipe(delay(500)),
    from([10,11,12])
  ]

  const $forkJoin = forkJoin(observables);

  $forkJoin.subscribe(data=>{
    console.log('forkjoin data', data); // [3,12] as forkJoin will return last emitted values of each observable
  })
In this example, `forkJoin` takes an array of observables, including two observables that emit 'A' and 'B' respectively after a delay, and an observable that throws an error after a delay. `forkJoin` waits for all the observables to complete, and once they complete, it emits an array of the last emitted values from each observable. However, if any of the observables in `forkJoin` throws an error, the error will be propagated to the error callback of the `subscribe` method.