I've looked at some bariatric cookbooks and I do not think they are worthwhile. There are tons of free recipes available on the internet. After the first couple of months, you don't really need bariatric-specific recipes (but don't sleep on the ricotta bake -- it is delicious and I made it regularly during my pureed and soft food stages).
I have found a lot of wonderful recipes on Pinterest. I've had the best luck searching for "skinny" and "WW" (Weight Watchers). "Healthy," "low-carb," and "keto" also have some good results; you just have to make sure they meet your requirements ("keto" recipes in particular can be a mixed bag, because some of them are very high in fat, which can cause dumping for bariatric patients).