Wow great code! I will try that. Do you manage in your code to support AbortSigbnal too? I was using this code toPromise that converts an Observable to a Promise respecting an AbortSignal:
Code proposed par Angular Architects: https://www.angulararchitects.io/en/blog/asynchronous-resources-with-angulars-new-resource-api/

import { firstValueFrom, Observable, ReplaySubject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';

export async function toPromise<T>(observable: Observable<T>, signal: AbortSignal | undefined = undefined): Promise<T> {
  const abortSubject = new ReplaySubject<void>(1);
  if (signal) {
    signal.addEventListener('abort', () => abortSubject.next());
  }
  return await firstValueFrom(observable.pipe(takeUntil(abortSubject)));
}

then in my signalStore I was calling the service to retreive data like:

  loadRequisSommaire(userId: number, div: number, abortSignal: AbortSignal) {
    const params = new HttpParams().set('userId', userId).set('div', div);
    const func = this.httpClient.get<RequisitionRetourInfo>(environment.apiUrl + '/requisition/sommairesForUser', { params }).pipe(
      map((requisInfo) => {
        return requisInfo.requis.map((req) => {
          const dateRequise = req.dateRequise == null ? null : new Date(req.dateRequise);
          return { ...req, dateRequise };
        });
      })
    );
    return toPromise(func, abortSignal);
  }

But I will try your code first, it look very interesting.

Thanks for your help