what do you mean by “angle shader brush”?
you can load multiple colours with painter since ver. IX was released, it’s the second eye-dropper icon in color mixer pallete (cmd+2/ctrl+2)
artists oils and realbristle brushes are showing the most pronounced colour mixing effect afaik.
you can use glow brush in FX category as photoshop’s color dodge replacement, works fine.
I’m not sure about color burn in painter though.
you can also resize the layers palette -