To improve the glass texture I changed it back to principled BSDF and changed transmission weight. I also did this with the lemonade, but the weight for glass was more than for the colored liquid.
For the model I simply modified the object inside the glass and pitcher to resemble liquid, but for the animation, I used liquid simulation, and modeled ice cubes to be dropped into the glass and collide with the liquid. Modeling the ice cubes was very fun, especially since I did the texturing for it in the textures tab rather than my usual shader editor and it provided a great result.