[Google Pixel 7 Pro] simplepinoi177:
I remember waaayyyy back in the Pixel 2 XL days someone was able to somehow manually untick the "oem unlocking" toggle (via some kind of trick or somehow forced "under the hood"), but when it came to the "fastboot unlock bootloader", it couldn't be done; apparently unticking wasn't enough to "trick" the device/bootloader. It was then determined that it seemed that when the device would connect to the internet or network (sim), it would somehow check with the server and, if it were determined to be verizon's, something would trip and it would lock down the bootloader permanently.

There was a small non-technical exploit that was used early on (during the first few months of release) where there was this widespread screen issue (where Google even extended manufacturer warranty from 2 years to 3 years) that, because of demand on returns, if one were to send for a replacement RMA, one had a good chance of getting back a phone that, if you didn't connect it to the network during initial setup, you could OEM unlock untick it before it was locked down by Verizon -- which so happens to be how I was able to get my Verizon Pixel 2 XL rooted. But, eventually, the demand to exchange devices ramped down and demand wasn't filled any longer by Google just giving Verizon devices to replace that this "exploit" was patched up -- I know because when my device broke later on, I tried to do this again and was only sent Verizon locked bootloader devices as replacements. Coincidentally enough, I was sent some devices from Google's RMA where I could initially untick "oem unlocking", but it would go back to being greyed out after a reboot, and uBreakiFix stated that the IMEI would be in some weird limbo of being "kinda Verizon, kinda Google store" and that's why; they even replaced the motherboard and had a whole new IMEI, and it looks like something was physically tripped on the board to disable the ability to unlock the bootloader. And because of the IMEI hiccup, Google wouldn't send me a Google Store variant knowing I purchased mine at Verizon.

It looks like there's a batch of devices that Google has a set range of IMEI's that are earmarked for Verizon, and when the device first connects to a network, it checks against that list to see whether to permanently lockdown the bootloader or not. I think that when Verizon gets their devices from Google, they actually turn the device on and connect it, have it "trip" the permanent lockdown, and then they factory reset the device and send it out to be purchased. I also think that that's why, when Verizon and Google were trying to keep up with the demand of getting devices replaced because of the screen bug/defect at launch, Google just gave them whatever they had in stock that was handy to keep up with demand, whether they were earmarked under that blacklisted range of IMEI's or, and why it didn't work months later after all the defected units were replaced.

Basically (TL;DR), historically, manually forcefully unticking the "oem unlocking" wasn't enough to get bootloader unlocked; it seems there might be a set range of IMEI's that are blacklisted under Verizon's restrictions, and that this may be permanently (physically, may be like Knox) tripped before Verizon sends out the devices to be purchased or obtained by the consumer. In the debacle/exploit I described, it was easier to work an "exploit" before this happened rather than to try and reverse the consequence after the device conferred with whatever server check and permanently locked the bootloader (I imagine quite as impossible as un-tripping Knox) -- I imagine akin to "unring[ing] a bell" or "crying over spilt milk".

I say all this not to discourage you, but in hopes of describing what has happened historically so you might refer to it and/or for anyone else who is attempting what you are trying to as well as telling you my experiences in hopes that it might help fill in some blanks and give you some idea as a way to get around certain things. I honestly hope you do find a way through as that would be amazing. I remember in Pixel 2 and Pixel 3 threads, there was a bounty of over $1000 gathered to find an exploit, so I hope that would happen for you if you figure it out!