Vlack The 8 series has distinctly better security than the 7 series, and also has hardware support for displaying the screen over USB-C. They are more expensive but there is also genuine value.
If a refurbished Pixel is a refurbished Verizon Pixel, it just won't OEM-unlock ever. If it is a refurbished "factory unlocked" Pixel, it may well be fine. If it is "carrier unlocked", who knows?
Perhaps the seller is willing to put in writing that the device can be OEM unlocked? Or perhaps the sale will include a reasonable return period?