postmodernWeston (the Wayland example/reference compositor) added a custom Lua based shell that you can configure/extend with Lua. I wonder how much work it would take to build a mruby Weston shell? I would prefer a Ruby DSL over Lua.
Here is the source code for the Weston Lua shell.
If you've never tried Weston, it supports using different desktop "shells", such as the kiosk shell which just runs a single window in fullscreen mode. These shells can also be configured via `.ini` config files.
https://wayland.pages.freedesktop.org/weston/toc/kiosk-shell.html
Using Lua as the configuration syntax or plugin system for a Window Manager isn't a new idea. AwesomeWM , a X11 Window Manager, uses Lua as it's configuration syntax. Now imagine being able to customize your fancy wayland tiling WM or add additional functionality with simple Ruby scripts running under mruby.
Another free project idea: write a generic waybar module that embeds mruby so you could write waybar modules entirely in Ruby.
Currently, waybar "modules" (their term for widgets that are displayed in the bar) are written in C++ and are initiaized with optional JSON data from `~/.config/waybar/config.jsonc`.
There's even a "custom" waybar module that supports various triggers/actions defined via JSON. A similar module could be written using mruby that calls DSL methods defined in a Ruby config file.
https://github.com/Alexays/Waybar/blob/master/src/modules/custom.cpp
https://man.archlinux.org/man/waybar-custom.5.en
