[cardanome]

Well, the Godot editor is actually a Godot applications, they are dog-fooding their own UI.

So it is absolutely possible to create complex applications with it.

Games engines are generally not used for apps, as games are optimized differently to apps. Games need to run smoothly at a high refresh rates at all times while apps can not hog all CPU power but need also be optimized to not needlessly drain the battery. This is no an issue in Godot specifically because it offers a low processor usage mode though.

So yes, Godot is a decent solution for apps. Only real issue is support for accessibility. There are screen reader plugins but if you want to do it properly, you might be better of with an app using native elements.