Pixel 3 and Pixel 3 XL phones sold by Verizon do not support SIM cards from other carriers unless they are activated on Verizon's network for the first time. Verizon spokesman confirmed The Verge pointing to a new policy implemented earlier this year to prevent thieves from targeting their retailers and authorized resellers.
If Pixel 3 (or one of Verizon's other current phones) is enabled, the company automatically unlocks the device "overnight" on the same day. There is not much time to wait to solve this problem, but all wait equally. Verizon is the exclusive telecommunications company in the United States. So your only alternative – and one of the other carriers is obviously buying directly from Google. Google seems to be handling stocks well. (Most storage and color options are available within a week.) However, delivery is not immediate.
This policy says Best Buy and is a barrier to those who want to fully purchase Pixel 3 at full price for use by their mobile carriers. (Most of Best Buy's stores probably will not allow this.) However, be careful when purchasing a new, unactivated Verizon Pixel 3 online.
Before you can use it elsewhere, you need to find a simple way to activate it in Verizon. I asked a friend or family member if Verizon's SIM card could be unlocked for a minute or two when launched.
The original pixel and pixel 2 was released before this policy was enforced. They were instantly unlocked and compatible with most major networks.