Why no examples of how "beautiful" this library is?

You have to head to the documentation to see an example. It is still Rust, which is a bit of an acquired taste so keeping that beauty off the main page makes sense.

I got a 404 when heading to the examples.

Because it’s GTK4 and it’s expected that you know what that is if you’re using this.

And if you're unfamiliar, there's widget galleries for GTK4 and Libadwaita both:

https://docs.gtk.org/gtk4/visual_index.html

https://gnome.pages.gitlab.gnome.org/libadwaita/doc/main/wid...

What do you mean, there's a screenshot link right there in the docs: https://docs.rs/crate/relm4/assets/screenshots /s