Does this mean you need one binary per OS so that the runtime matches, or do they do some magic so that one single binary can run on all Oses ?
You of course have to choose your target platform for this as it makes .exes for Windows, ELFs for Linux, etc.
If you want you can still choose to distribute IL DLLs and users then use their already installed dotnet on their machine to run them.
https://github.com/jart/cosmopolitan
(but, yeah, you probably want one version per target, even if hacks are cool)