A themecompiler would be nice. You throw in your needs ae vectors or as the description of those and the compiler spits the theme. That are both persectives of course.
Vector based creating of images during runtime of REAPER would be same pure waste of energy as creating websides that deliver static content with the help of php f.i.
GPU could be a way. But luckly we don't have to look at computerspecifics concerning graficcards when using REAPER as a DAW. REAPER can run on very small hardware like raspberry. Maybe it's wise to keep this strategy.
And you can make pulsating knobs with a bunch of fixed images. I dealt with knobfiles just to achieve this.
https://www.g200kg.com/en/webknobman/gallery.php