My dog has been eating people for a little under a year. When I tried to switch him to dog food, he puked after about 5 pieces. The next day it was the same after about 10 pieces.
Answer by morrissey is god
sneak some into human food, as he starts to get use to it and does better on it.
Then increase a bit each time he makes the adjustment to the new amount.
It’ll be a slow process but it should work.