It looks like Google didn't want to put up with the same screen burn-in and responsiveness issues with its Pixel 3, instead turning to LG's rival Samsung for its AMOLED panels. Google says the Pixel 3 is the first device to ship with this capability.
As you may recall, earlier this year we began locking phones until they were initially activated on the Verizon network to prevent theft and protect employees.
However, there's a procedure in place to automatically unlock the phones. According to an Android Central reader, "putting a Verizon SIM in it, the phone worked fine - but it complained again as soon as it had another US SIM inserted".
Typically, the only reason why a Pixel would be SIM locked is if it was being sold by Verizon - or Best Buy as a Verizon reseller - on a multi-month financing plan. In past years, Verizon has sold SIM-unlocked Pixels that worked on every carrier - indeed, all its phones were unlocked because of a legal agreement it made a decade ago.
Following a short pre-order period, the Pixel 3 and Pixel 3 XL are now shipping to customers in the United States and several other countries, including new markets such as France and Japan. The trick seems to be waiting for a day for Verizon to automatically unlock it.
In the USA, you can grab the Pixel 3 directly from Google or Project Fi in 64GB guise for $799 or $899 for the 128GB version. That means even the iPhone XR, which is available for preorder right now, will be briefly locked to Verizon. You'll just have to accept the trade-off of not being able to get any incentives Best Buy and/or Verizon are offering with purchase.