I can confirm 100% that Sony a7R III cameras have Arrived in the USA!
One large retailer (who I cannot mention by name) confirms they have received a very large shipment today that should cover most of their pre-orders. Since this retailer does not charge pre-orders until the product is in stock, you may get confirmation that your camera is in stock once when you see that your order has processed.
Availability date is still listed as November 30, which is quite likely required by Sony so that all retailers receive their allotments before any cameras are released.
But once again, Sony a7R III cameras are in the USA!