Gio looks really neat (from the demos), I will definitely try it out as I have been looking for a nice way to build desktop app for quite some time.
Other projects that I am considering to use: https://github.com/wailsapp/wails (looks very decent and I would be happy to use Vue.js for a UI bit) and Flutter with desktop support (https://github.com/google/flutter-desktop-embedding, in this case it's not directly using Go but you can bind them together).
If this would mean that I can just use Go for everything - that's great but the only concern for me I guess is just the availability of examples and widgets. I don't consider myself a good UI designer so relying on libraries is important :)