a rust with gc is already available. it is called c# and runs on all os nowerdays

No, a class-based OO language where you need to spend effort crafting build targets by hand or use an IDE to define how to build is not anything close to what I'm talking about. If you think that it's "Rust with GC", I think you're misunderstanding what actually appeals to most people about Rust.

I'd also argue that "runs on all OS" is true, but "is easy to develop without extra work in a cross-platform way" is not. I've never cloned a Rust project and had trouble building out of the box on Linux, but I'd estimate maybe one out of 20 C# projects I clone from Github build for me out of the box with `dotnet build`; the rest either require me manually tweaking the build configs to avoid stuff like hardcoded Windows-style paths or link to system dependencies that don't exist on Linux. I imagine you might argue that this is a property of how people use the language rather than the language itself, but that doesn't really matter from the standpoint of whether it's worth it for developers who don't use Windows to spend any time trying to invest in the ecosystem.