A few months ago I stumbled across this extension (https://www.omglinux.com/space-bar-gnome-extension), which sparked the idea of having a dynamic indicator rather than just a static icon.
We used the extension for some very hacky experiments, e.g. this from @cassidy:
This seemed promising enough that @verdre built a proper extension for it, which implements the exact visuals and behavior we wanted (though still very hacky code-wise).
This is what we showed off during the design state of the union talk at GUADEC: