Tangential reply, but Druid has been abandoned. The spirit lives on as Xilem, but that doesn't have much traction either. It's very... exploratory in nature.

I'm partial to iced, which to me is the best GUI library in Rust by far. The Discord is super active if you have questions.

https://iced.rs/

Slint is backed by a company that sponsors its development, in model similar to Qt.

I'm curious as well. My understanding is one notable differencse, exemplified here, is that Slint can work on embedded devices / no-std.