Well there's the web based Figma, somebody even created an unofficial desktop app for Linux. Figma has plugins, tons of them for many graphic design tasks. It blows the Affinity stuff out of the water imo.
Additionally, it’s very much geared specifically toward UI design and prototyping, whereas something like Affinity Designer or Sketch also work well for generic screen-targeted vector work.
True for project files, but you can export images and SVGs.
> it’s very much geared specifically toward UI design and prototyping, whereas something like Affinity Designer or Sketch also work well for generic screen-targeted vector work.
That's where the plugin ecosystem comes in. It's quite usable for simple/modern vector work that's more component oriented graphic design than hands on illustration.