Make character styles that apply only a swatch color, no other attributes. You can apply this to any paragraph, so you do not need to redefine any paragraph styles. However, a bullet is defined within the paragraph style, and I have not found an easy way to change the color of the bullet without changing the bullet definition in the style or replacing the swatch – which is not what you want if you are using several bullet colors in one document. Find/Change does not seem to recognize the bullet character separately when it is part of a styled paragraph. Perhaps someone who is more familiar with GREP can help you with changing just the bullet colors within that style.

With the object styles, I don't know an easier way than to duplicate the style and change the swatch color. That would also allow you to use Find/Replace to change format to switch the object colors if you want to do it afterwards.