Actually, I purchased my 128GB iPad Pro + LTE through Apple.com. They have Verizon option, but you have to add the Verizon nano SIM to the order (it is shipped separately). The iPads come with the Apple SIM by default.
If you don't ask for the Verizon SIM at order time, you can call Verizon and request one or walk into any Verizon store and they will give you one when you activate service.