Sounds like my Moto G5s Plus. I updated it to Android 8.1 and it started having issues like lagging, completely freezing up, randomly restarting, battery drain, overheating, etc.
Oh, well. It ran PixelExperience 11 just fine. It also allowed me to use the notification LED that Motorola disabled in software for reasons unknown.

Edit: I just like this part from bootloader unlock license agreement on what doing so may cause:

Cause the Device to overheat, explode and/or catch fire, exceed SAR values, exceed safe volume settings, and otherwise be unsafe, including creating the potential to cause serious bodily injury, including death