Is a Dip Belt Necessary for Weighted Dips and Pullups

I have reached a point where I can do fifteen bodyweight dips easily and I want to start adding weight. I am wondering if a dip belt is necessary or if I can just hold a dumbbell between my feet. I have tried the dumbbell method but it feels very awkward and I am worried about dropping it.

A proper leather dip belt with a chain seems much more secure but I am not sure if it is worth the thirty dollars. I have seen some nylon ones as well which are a bit cheaper. I mostly want to use it for weighted pullups as well to build some more upper body mass.

Do you find that a dip belt changes your form at all? I am worried about the weight pulling me forward too much. If you have a favorite brand of dip belt that is comfortable on the lower back please share it. I am ready to take my calisthenics to the next level.