You should be able to fastboot boot TWRP which will let you decrypt your data. The LineageOS recovery just doesn’t decrypt data nor prompt for pin/password to decrypt it.
I think you should be able to just LOS again as if it was an update from the recovery (make sure to also flash Gapps and other addons you had, as flashing from recovery does NOT preserve anything and booting without Gapps if you had them will permanently wreck some state.
I’d use TWRP to decrypt and pull out the data for safety, then you can try flashing LOS again.
ser