Currently, Plasma/Dolphin supports colorized directories icons. If main system color is red, directories icons would be red.

I think these icons are loaded from scalable vector graphic files.

Many years ago people use bitmap with palette. Palette assign color to 8-bit value.
Maybe do similar solution, but assign system function to 8/16/24/32-bit value. Maybe use one bit from alpha channel to distinguish it is function bit or color bit?

And, which function we would provide:
1. Set alpha channel to some value
2. System active element color, system inactive element color, system text color, etc.

What do you think? This could solve many problems, since actually many icons are still delivered as bitmap.

That is not typical brainstorm. I do not search for similar solution, for also asks there exist similar solution.