I am looking for something that is purely written in go.
I presume that what you actually want is to display images, video and other GUI stuff from your program written in Go. If there are libraries available to do that then why care what language they are written in?
At the bottom of the software stack you are using Linux, written in C, and most probably X Windows, again written in C. Why worry about what language the GUI library is written in?
Memory in C++ is a leaky abstraction .