Easiest to just make your own, IMO, using Epsom Salt, Lite Salt, and Potassium Chloride powder. It’s what I do. Just look up the RDA for each element and make sure you have enough of each in your final mix.
Ultima electrolytes help me usually. No sugar, no sucralose. It has little bit of stevia but have all needed electrolytes to help you get through fast. I use it and helps not kicking me out of fasted state. It is also no calories. Local Walmart or natural grocers of whole foods have it