Regard '21 F-150, the dealership nearest me has 82 in stock. The second closest has 73. I'm not doubting those that say the dealerships near them are empty, just that that doesn't seem to be the case around me. That could be that a lot of these vehicles come in through the Port of Houston, and thus Houston tends to get the largest and best pick of the bunch (I heard someone claim that years ago) or that trucks are such big sellers around here.
Regardless, I take that to mean that I wouldn't trust any rumors about the Raptor release date based off what you see at your local dealership. Just wait for Ford to make official annoucements... and expect dates to move around a lot.