Only if you have no dependencies and interact in no way with any platform-specified services. Now certainly there are platform-specific things with Rust as wel

Only if you have no dependencies and interact in no way with any platform-specified services. Now certainly there are platform-specific things with Rust as well, but the defaults are structured in such a way that exposed APIs are more likely than not to be platform independent--you have to go out of your way to break compatibility, rather than it being the default. And once you get your binary to compile, the static linking means there isn't runtime dependencies that might break either. The net result is that given a piece of rust code, it is far more likely than its C equivalent to compile on a new platform. And once it does compile, it can be run in any context without concern for differences in the runtime environment. The Rust compiler may target fewer platforms, and therefore be "less portable" in that sense, but if it is a supported backend then it is going to be easier to get the code working.