It really depends what you want to do, but in general I would say: the HTML Canvas and the web in general. WebGL for 3D, or rather a framework like threejs or babylonjs.
Doing it not on the web, but still cross-platform makes only sense, if you need the maximum performance, or if you already have a working toolchain you are familiar with. But since you don't want to write OpenGL or Vulkan code and you are not familiar with it - I think you are up for great adventures by diving into Skia and co. There is a reason the web became sort of standard for cross platform despite its numerous flaws - the alternative is likely more pain. But maybe not, depending on your skill set. But since you did not mention Qt, I would assume you are new in the area in general? Then I really recommend the web.