and for a quick overview of other GUI solutions: https://lispcookbook.github.io/cl-cookbook/gui.html (Gtk4, Qt4 and 5, LispWorks' CAPI (incl. for mobile runtimes), IUP…)

I have been pleasantly surprised lately to discover surprisingly nice-looking Tk themes (like https://github.com/rdbende/Forest-ttk-theme). We can use them from CL too, with the nodgui library :) (see link)