It sounds like you are dropping the replacement shake but in case you did want to try a Newcastle style diet again I found the PHD Diet Whey powder was the "best" commonly available alternative (Amazon, Tesco, H&B).
Full details here:
https://www.phd-supplements.com/diet-whey-powder.html
The important number is the carb value - 2.75g per serving - which is a lot better than most replacement powders.
I fully agree with everyone saying that real food is best but also understand that a
short term intensive "attack" does have good results for a lot of people. Shortly after I was first diagnosed I did 8 weeks of on a max 800 calorie a day diet and saw amazing results in peak BG levels and stability. This was only possible by drinking two shakes (breakfast and lunch) then a vegetable stew or stir fry in the evening. It was not the most enjoyable 8 weeks but the results were worth it. After that I dropped the shakes, relaxed the calorie limit but stuck to Low Carb and have continued to see improvements.