Pancreatitis and food

So, my 10 year old fixed, male dog was just diagnosed with chronic pancreatitis. We are waiting for labs to come back to see if he has Cushing’s but it is super likely.

The vet has switched us to Hill’s z/d which is hydrolyzed soy. The canned version $76 for 12 cans and $140 for the large bag of dry. We have to give him 4.5 cups of dry or 4.25 cans of food. He does like the canned food but i can’t spend $76 every 3 days on canned food.

Due to price and my dog’s extreme pickiness, i asked the vet about alternative foods and was told we could switched to Royal Canin but they won’t approve the canned version bc it is pork and not hydrolyzed soy and ‘we are also aiming to minimize the number of ingredients in his meals.’ They also won’t approve SquarePet Low Fat Formula bc it isn’t Rx. They said i cannot give him any food toppers, bone broths, treats, or anything but a vegan marshmallow so he will take his medication and a couple baby carrots as treats.

I have seen so many people talking about how SquarePet worked for their dog and how they give their dogs bone broths and other things and i can’t tell if our vet is being extremely rigid or is just not thinking past Rx only. What the heck do they do for people who truly cannot afford to spend $140 on a bag of food?

At current, my dog will eat most of his food at night but won’t eat in the mornings and is not eating anywhere close to 4.5 cups of food (more like 2.5 cups). I cannot leave his food out all day for him to eat whenever he chooses, we have cats who will try to eat it and the dog will absolutely try to attack the for messing with his food even if he doesn’t want to eat it. am already so incredibly frustrated with all of this and am at a loss on what to do to get my dog to eat and keep him in compliance with the vet’s recommendations and guidelines. Does anyone have any insight or advice?