Read the Vegetarian Myth for info on soy! Just finished it yesterday. Very small amounts cause huge problems! You can probably find it at your local library. I wouldn't drink the shakes.
Why not make your own? 3 home-pasteurized eggs (boil egg for 45 seconds only-tx Dr. Eades), 1/2 c coconut milk, 1/2 c ice, 1 cup frz fresh strawberries or other berry, or, if you don't have hypoglycemic issues a very small banana with 2 tbl nut butter - blend in Vitamix or blender. I did raw eggs once (Nature's Promise Omega) in my shake and got salmonella-ouch! Will NEVER eat raw eggs again. Even though a local pastured egg MIGHT be fine, my experience was so aversive that I'll never try again! Lower abd pain for 24 hrs - felt like someone was pulling at all my organs with a hook!
What about tins of sardines, olives, cheese if you do it, a few nuts won't hurt, grapefurit, 1/2 apple, berries, pre-cut raw veggies or salad fixings fixed ahead of time for the first week and have some meats pre-cooked for your first 1-3 days home. I also make and freeze meatballs and then just nuke and add (home made sauce) or a good quality jarred marinara. You can pre-cook spaghetti squash, strain and freeze too. Make a meatloaf, cool, slice and freeze portions. Make egg/bacon cupcakes thingys and freeze. Chicken stew made ahead of time would be great for your first couple days home esp. if you have anesthesia. You won't feel like eating much your first 24 hrs. You could also make bone broth and freeze to take out mid week. That really keeps me for 4 hrs alone.
I keep meat babyfood on hand for when my dog gets sick. I also tell my puppy clients to have it on hand for their spay/neuter as most pups can only handle 2 oz of meat at a time every 2 hrs. (For those who like to be in the kitchen, I suggest boiling chicken breast and saving the broth.)