What is the current GUI/App framework du jour?

I'm a game dev by trade but want to work on some software in my spare time.

I'm looking at the best cross-platform gui/app development frameworks around and there's roughly 6 billion to choose from, so which is the latest and best?

I want to support Windows, MacOS and Linux, and possibly mobile apps later.

I will need to access underlying system APIs for each platform, possibly through my own abstraction API.

Last I checked, Electron was the in-thing, but that was a year or two ago and I wasn't really much of a fan of the concept, but understand that's the way things are now for an attractive and cross platform GUI.

Thanks in advance.