Hi and Welcome to YT! Sorry about your pup.... but don't give up yet....
First, I'd find a specialist with a bit more positive outlook. LS surgery is 80-90% successful at the University of Tennesee.
Once the shunt is repaired, the kidney stones will dissolve on their own (change in chemistry). This is a common occurance in dogs with LS.
Right now, get him on Hill's Prescription L/D (low protein liver diet), Lactulose (stops the absorbtion of ammonia in the intestines contributing to the kidney stones), and Denamarin (contains Milk Thistle and SamE Liver protectant and detox). You can also add some coconut oil to his food.
Join the group
Liver_Shunt_And_MVD_Support : Liver Shunt & MVD/HMD Support
They can help find a specialist. Read about LS at
Portosystemic Shunts FAQ