With /e/OS, the bootloader can be relocked on Fairphone, Shiftphone, Teracube, and Google Pixel, and they are sold locked by Murena. https://community.e.foundation/t/list-devices-where-bootloader-can-be-relocked/48424
this was one of the things i've been waiting for! i was leaning towards graphene because of the bootloader lock, but i don't want a pixel.
the next problem i have to wait for is better support for the network bands in north america. i know from experience that the bands that fairphone supports are the same that my chinese phones supported in the past; which meant that i got no signal inside of large buildings and had to rely on wifi. i've never heard of shiftphone nor teracube, so i hope that their band support is better.