That has nothing to do with the UI framework. The X11 dependency comes as part of the clipboard integration (which I'd argue should be optional or even removed). Still, I wouldn't call it modern if Wayland is outright not supported.
What's modern about Wayland?
I think this is only a problem when building from source, right? It is indeed because of the dependency on https://github.com/golang-design/clipboard.
I hesitated a bit bringing in this feature. On one hand, I really like to have clipboard support, on the other hand, I don't like that it requires you to change from static to dynamic linking (and have the x11 dependency).
Maybe I could write an install.sh script for installation that detects the OS and fetches the correct version/tarball from the Github release.