I have been interested in using GrapheneOS but hesitant about actually getting a Pixel phone. Used phone prices are usually >$300 even for "a" series unless I go back several generations. Whether the device bootloader can be unlocked is also a question. I am definitely not ready to spend $449 on a new Pixel 10a.
Side note: I did get the 10a on launch from Google Fi for ~300.
Used is a gamble due to improper OEM unlocking practices, so make sure it has a good return policy and try to verify OEM unlocking is accessible if you purchase used.
Basically, buy a Pixel 6 or later (I suggest Pixel 7 or later, since Pixel 6 will be minimal support soon) that you are sure has an unlockable bootloader. The majority you'll see don't have an unlockable bootloader.
Which mostly means either buy direct from Google, or buy one on eBay that already has GrapheneOS/CalyxOS/LineageOS on it or for which the seller expressly says it has an unlockable bootloader.
(IME, don't bother trying to ask a seller to check bootloader, if they haven't already said. Almost no one is going to go through the process to check, the answer is probably no anyway, they might misunderstand your question and answer that it's "unlocked", and they may be tired of people asking.)
Then I decided everyone who knows about bootloader unlocking would've already checked and mentioned if it was unlockable (but not if it wasn't, since why confuse normal buyers with a fringe thing), and I've never gotten a positive response trying to tell any seller about it, so I think I'm just wasting everyone's time.
Your mileage may vary.
Yeah, do that.
It’ll still be the snappiest phone you’ve ever used.