To learn Web programming, Iโd suggest not using any Web packages. Rather, start with net/http from the standard library. It is easy to write a small Web server with net/http, and you learn more from that than from using some Web framework.
I cannot comment on GUIโs. There are a lot of them - browser based, Electron based, based on some native UI lib (Qt, wxWidgets,โฆ) or on OpenGL, etc. etc., and to my knowledge, there is none that has become some kind of de-facto standard in the Go community.