Got the Pixel 3 XL in from BackMarket.com earlier today. Seems to be pretty legit.
1. I ordered the Google Pixel 3 XL 128GB - black model, but got the 64GB model instead. Reached out to them and they got back with me quickly, but the follow up has taken a while.
Hello, We apologize for the inconvenience. We can offer a partial refund for the difference of GB storage if you wish to keep the device. Please let us know how you would like to proceed. Thank you
I emailed them back saying I would like to know how much the partial refund will be. I can make a new order for the 64GB model on their site for $150 less than what I paid for the 128GB model. So if the partial refund is less than $150 then I will attempt to send it back for a 100% refund and order the 64GB model.
The phone is in excellent shape otherwise. I didn't notice any scratches or anything signs of excessive use. Phone was fully charged when I got it so I begin transferring everything off my old Pixel 3 XL onto the new one. Really easy process, by the way. It wasn't until I entered the IMIE number on the phone into my Verizon account to get it activated that I realized it was a 64GB model.

So the phone was accepted by Verizon.
I kind of want the 128GB model, but if they refund at least $150 I'll keep the 64GB model.