Finally decided to give GrapheneOS a try as I've got a fp6 with /e/os and love it.

Found an eBay listing for one in very good condition, and right in the subject it says unlocked. Got it yesterday, excited to try it. Start following the install instructions, only to see OEM unlock grayed out. One article says, it must be connected to the internet, so I connect it to wifi. Still grayed out. Another article says install all the updates and reboot. Two hours later, still grayed out. I've measaged the seller asking for a refund, but I don't know. Anyone else have an idea?