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.