how does Skia and pdf work together? I know there is a pdf backend but the way I understand it is that it just outputs pdf instead of an image I recently start

how does Skia and pdf work together? I know there is a pdf backend but the way I understand it is that it just outputs pdf instead of an image I recently started playing around with wasm Skia/CanvasKit but I have a hard time wrapping my head around what exactly it is supposed to be used for, as well as Skia in general. For example, Skia allows text rendering and I could naively assume that if I want to build some high performance 2D UI that Rendering text with Skia would work reasonably well. But at what level would text interactivity like selecting text happen? I’m afraid this is a very generic question. Are you familiar with any pdf or text related project that uses Skia and could help me better understand what role Skia plays?