There's Tk (https://tkdocs.com) with bindings to several languages. The simplest...

		libx on Aug 23, 2020 \| parent \| context \| favorite \| on: Ask HN: How to do cross platform GUI? There's Tk (https://tkdocs.com) with bindings to several languages. The simplest and the original one being TCL. What a great language to program in! Although I've not yet tried it myself, there's AndroWish (https://www.androwish.org/home/home). Deploy your TCL/Tk code on Android with minimal changes.

I used the Tk ruby bindings several years ago and it was easy and looked decent.