On the iode forum, they say it’s only the Fairphone 4 that can relock the bootloader, and the FP 4 is a lot more expensive than both their Pixel 5 and 6.
If you can only afford the cheapest refurbished phone, you can probably still get a cheaper phone by buying one on the 2nd hand market and installing LineageOS yourself, and if you can afford a pixel phone then GrapheneOS is still a better option than iode.