Keto also makes a milk substitute that tastes almost exactly like fresh milk (not soy) when cold (don't heat it, yuck). It's called Keto Milk. Heck, they even make a Chocolate Milk powder

Also, many (most?) longtime low carbers mix cream and cold water, add a pinch of salt (and sometimes just a pinch of sweetener) and use that for milk, it works great.

Another option is Almond Milk. This has a milder flavour than Soy Milk and some great nutrients. Can often be found in the Health Food Store ready-made and I think there's a recipe or two in the Kitchen Forum, a great place to look around.

Hope this helps.