Get values from observable before completion: find does not work

[SimoneMSR]

Hello! I write to ask help for finding a solution.
I have an Obs (produceObs) that is zipped with another (consumeObs), so that value is emitted only when a consume message is send (within consumeObs). In this way a queue of to-be-emitted values creates (within the produeObs). What I would like to do, at some point, is to check wheter in produceObs I have some kind of values, even if they have not yet consumed. Can I do that?

I tried to solve using find with this stackblitz, but without success: the operator returns only when the values I look for are consumed.

Here is the main code

var messageConsumed = new Subject<string>();
var enqueuedMessage = new Subject<string>();

function read() {
  emit('read');
}

function write() {
  emit('write');
}
function emit(s: string) {
  enqueuedMessage.next(s);
}

function consume() {
  messageConsumed.next('');
}

messageConsumed
  .pipe(zip(enqueuedMessage.pipe(filter((x) => x != null))))
  .pipe(concatMap((x) => of(x).pipe(delay(100))))
  .subscribe((message) => {
    console.log(message);
  });

function find2() {
  enqueuedMessage
    .pipe(
      find((x) => x == 'write'),
      take(1)
    )
    .subscribe((x) => {
      console.log(x == undefined ? 'not found' : 'found!');
    });
}