If you want to make something for fun, or you're doing embedded, it's a fine choice.
But if you're making the default "GUI for CRUD" style app and you use Rust: You either really really hate your employer, or you're in it for the fun more than you realize.
The amount of prior art and resources you're just tossing in the dumpster is insane. Take mobile: For a real product are you going to go and re-implement years of accessibility and internationalization, re-implement platform standard UI paradigms, and god knows what else just to be able to use a specialized framework in more niche language?
Combine that with the fact that hiring for Rust is going to be massively more expensive and painful than any default and you'll be at the point where you probably could have hired teams to do each platform natively.
IMHO, rust is more explicit memory management than manual memory management. You don't have to juggle individual calls to malloc and free, but of course there is the borrow checker and you also have to be explicit about things like taking a reference to something versus cloning it.
Thanks to all that, nobody's yet managed to demonstrate a GUI library that really feels like it belongs (in terms of code architecture, but also look & feel).