Carrier-sold Pixels generally don't have "OEM-unlockable" bootloaders.

Your best bet for now is to buy a new Pixel direct from Google, or a used one from eBay that the seller advertises as already having GrapheneOS on it (or otherwise guarantees that the bootloader is unlockable). These ones are worth a lot more than the ones that can only run Google/carrier Android.

https://grapheneos.org/install/web#prerequisites

I own two GrapheneOS Pixel 7 units, which should get any Google blob security updates (which GrapheneOS incorporates) through October 2027, and GrapheneOS may still support it with source updates after that. So in a year or so, I might get the GrapheneOS Motorola if it's available, or a later Pixel. (I never buy these new, since I don't want to carry a several hundred dollar phone when a 2 gen old one is still great, thanks to GrapheneOS.)

https://support.google.com/pixelphone/answer/4457705

I finally left Verizon after nearly 20 years. I had it with their enshittification, couldn't stand it anymore. I switched to US Mobile and on the Darkstar (AT&T) network. I have no regrets. I caught it on a black friday deal, so I'm paying basically $20/mo for top tier service. You wouldn't have caught me dead with an AT&T service or MVNO years ago because I'd seen so many bad experiences second-hand, but these days it's been a breeze knock on wood

I also did the math and determined buying a new unlocked phone outright on this plan was far cheaper than paying Verizon monthly for one.