how do I make sure the pixels 7a I buy is completely relockable, including bootloader, on non-stock software?
I visited 3 stores looking for the pixels 7a. One of these stores (best buy) sells it at a 20% discount for only 2 weeks, brand new, 128 GB, so I may go for it to buy and nuke to install graphene OS, then relock it.
A poster suggested me to avoid verizon, because they lock the bootloader to prevent you installing anything else.
This one seems to be a pixels directly from google: on a table displaying other google devices and earbuds, but I wouldn't want to buy something I cannot relock on non-stock software.
I just picked up a 7a directly from Google, unlocked. That's honestly the only way I recommend going about it, especially if the plan is to install Graphene.
You don't need to worry about whether it's relockable, but it's important that it can be unlocked in the first place. Just don't get it from a carrier and you'll be fine. Buy the phone from some store like Best Buy.
Just don't get a carrier variant and you'll be fine. You can also check for sure by putting the device's IMEI into https://store.google.com/repair. For example, here's what mine says: Pixel 6 Pro Stormy Black 128GB (Unlocked) (Pristine)
I got my Pixel 8 Pro from Best Buy and it's unlocked. The other pixels come unlocked too, since they just get them from Google. I've been using Verizon as my carrier without any issue.
Bootloader relocking is supported with an alternative OS on a Pixel. GrapheneOS supplies an avb custom key and they expect that you use their OS with a locked bootloader.