foo.js

  scrollObservable.pipe(
    mergeMap(value => {
      const { currentPosition, maxPosition } = value;
      console.log("VAL: ", value);
      if(currentPosition >= maxPosition) {
        return getPokemon$(10).pipe(
          map(value2 => console.log("VAL2: ", value2))
        )
      }
    })
  ).subscribe(data => console.log(data));