

Unlocking the bootloader on a Pixel is relatively simple but you do need to boot the phone and get past initial setup.
You don’t need to attach your Google account even. You can skip all of that.
You just need to get into the Developer Settings section and enable “OEM unlocking”
Once that’s done you can proceed with your unlocked bootloader normally through ADB/fastboot








Gotcha. didn’t realize you meant the developer settings options was greyed out since your pic was just off the bootloader.
There are two possibilities here:
it needs to check in over the internet to enable OEM unlocking. Boot into the OS, connect to Wi-Fi, then do a factory reset from within the OS. Go through setup a second time then and it might enable OEM unlocking.
The device was not purchased fully and may have been on a payment plan. You can try contacting the various carriers and providing the IMEI to them and ask if the device appears in their inventory as still needing to be paid off. You might be able to convince them to unlock it for you.
Here is a reddit thread with some information that might help. Read all the comments. Several people have been able to get around this with different approaches (trying sim cards from other carriers, telling the carrier you’re an android developer, etc): https://www.reddit.com/r/GooglePixel/comments/sc2w1r/fyi_if_your_oem_unlock_is_greyed_out_after/
Good luck! You might just have to return it but it’s worth a try.