what is clear for certainty is that we have to wait for an announcement from Facebook. I hope this is not just a rumor so that the crypto world will grow and become more famous because there are already many great people in it.
i believe this in only a rumor and facebook wont ever create their own crypto because facebook has been a hater for cryptos . they ban crypto advertisement and post or even crypto related accounts . i also see that facebook has already have thier own electronic payment method or a wallet where you can put funds in it and use it directly under their platform . so with that , i dont think they will have a reason to built a crypto based coin .