Changing colors of the whole gauge color is good, but from a visual/design perspective, the ability to have gradients is something that would be a great feature. It is something that is possible with css and SVGs - but just, it seems, not possible in Perspective for components.
EDIT: Info on how to do this with css and SVGs: https://stackoverflow.com/questions/37328302/fill-an-svg-shape-with-a-gradient