Duit is a pure go (*), cross platform, MIT-licensed ui toolkit for developers. the api is small and uncomplicated.
duit works on the bsd’s, linux and macos. it should be easy to get running on plan 9. for now, use the windows subsystem for linux on windows.
(*) duit currently needs a helper tool called devdraw, from plan9port (aka plan 9 from user space). plan9port is available for most unix systems, with devdraw in an x11 and native macos variant.