We use the HSL color model in all of our designs to ensure consistency of lighter/darker shades (instead of relying on opacity where the color can be altered by the background).
We just converted all of our Color Styles to variables, but were disappointed to find that color variables only support HEX codes as values. Yes, I can click into the color and see the HSL values, but because the values themselves are HEX, it’s HEX that gets generated in the code, not HSL.
I see there is also an open idea here for RGBA support too, so perhaps the best approach would be supporting all color models in variables and allowing the user to set the model when they create the variable.