there’s no bootloader unlock for the Android line of BB devices. There are no roms out there… a BB employee even chipped in at…
https://community.e.foundation/t/blackberry-z10-is-it-possible/37707/2
There is currently no documented way to unlock their bootloaders, or else otherwise circumvent their protections, in order to install a 3rd party operating system. Until that challenge can be overcome no other real progress could be made with porting LineageOS to them.