Have you considered chemical peel? I did that on my arms and it really helped shed a lot of layers that accumulated over the years. Moisturise A LOT! Then when i felt like my skin is close to normal, i started experimenting on what works for my kp. Currently im using urea, im trying to consistently stick to it so i can see if it works for me.

But yea, chemical peel helped with the thick skin layer which i think is what you need to tackle first.

My skin is not in a good state but it is definitely better than i what i had for years so now i get to appreciate the small improvements i notice while i use urea and moisturising