Not an official answer, but from what I have tested after using for a week, Standalone (Win / OSX), Android and WebGL seem to work just fine. Minor bugs may happen but closed quickly by devs.

@JustinFincher thanks for the info. One more thing, is this useful for in-game UI (dialog / panel / HUD that takes only part of screen)? Just think about a RPG game with lots ui stuff. I'm curious because the documentation hints that this project is made for building "apps" for unity.

@favoyang In my perspective, UIWidgets works in a way that is similar to Dear IMGUI, which outputs a bitmap for drawing and hides internal hierarchy from the scene. So if you need to draw UI on a partial screen, you can give UIWidgetsPanel in the UGUI canvas a limited size or make your own child layout in a full-screen UIWidgetsPanel leaving the root level container a transparent background. I would prefer the latter approach because that would be better at handling notches and keyboard events in mobile devices. After all, I am just a user of this lib and I can't guarantee that what I am saying won't break in the future. 🤪