T-Mobile recently had a trade-in promotion where you could trade in any phone and get a pixel 10 for "free". The free is in quotes because what actually happens is you get signed up for device financing which spreads the cost of the phone over 2 years, and then they give your account a credit each month for the same amount charged by the device financing. So they'll end up charging you $33 per month and crediting you $33 per month, resulting in the phone actually being free. The catch is it locks you into 2 years on T-Mobile because if you cancel the account or pay off the phone early, you forfeit all the remaining credits.

Since it was free and I had no plans on leaving T-Mobile in the following 2 years, I went ahead and did the trade-in with an old Pixel 3a. What I didn't realize is since the phone is on a payment plan, the phone is not only carrier-locked (which would be fine) but also bootloader-locked until the end of those 2 years, so I cannot install GrapheneOS on it until ~2028. My free pixel 10 is sitting in its box gathering dust until 2028.

Here is a reddit thread discussing the trade-in promo as proof that it existed: https://www.reddit.com/r/tmobile/comments/1r0by30/pixel_10_f...