halloy is not only an awesome app but a fantastic example if you want to learn more about building GUI software with iced.
https://github.com/iced-rs/iced
If you're interested in building a GUI app in Rust, I encourage you to go through the examples and showcase apps like halloy
and if you get stuck, can ask our chill and helpful community on Discord https://discord.gg/3xZJ65GAhd
Funny enough, having close to zero experience with Rust and wanting to build an iced-rs application with Claude Code, I asked it to search github for large projects using iced-rs to use as a reference and Halloy ones one of the top 3.
I was just looking at that; I've been wanting a nice GUI library for Rust but never found one I liked. A number of them were bindings to other GUI stacks. I might try Iced next time I'm poking around with Rust.