I've mentioned imgui too, and posted link to your comment. It needs to be evaluated here too. Coming from the game development world, there is a big appeal to the framework. It's author is responsive, the size is small, and the features are really what a game tool, or in-game debug screen may want. Easy to integrate, with various gfx backends (opengl, direct3d, etc.), and supports things that are not even done well by some of the other frameworks - like docking (which I've mentioned in my post).

It has quirks, biggest one (to me), being how to deal when you have lots of widgets and their state (e.g. the hidden state labeling), then with my personal experiments I've found cases where the UI would lock, when flowing text, but overall seems to work well.

On the other end, I'm really happy (myself) with Flutter, but then it misses the stuff that I just mentioned, though for a mobile app - you may (and most likely not) need these requirements.

So two important, and recently new frameworks not included, I think they should... Flutter is direct competitor to Electron (now available on the desktop), and IMGUI to Qt/GTK.

Do you mean Dear ImGui? Isn't it a C++ GUI?

https://github.com/ocornut/imgui