[smaudet]

.net core is not Windows only - works on the big three (linux mac windows).

That said, I get where you are coming from - .net framework is pretty much just windows, and there a large number of libraries/apps that are Windows first, other platforms second.

If you do end up needing to do Windows dev, though, I'd recommend it, same as if I were doing Apple Dev I'd recommend Objective C/Swift, or recommend you brush up on bash/zsh/fish, C and maybe Xorg/Systemd for linux.

You can use other languages on all these platforms but the 'native' toolkit tends to enjoy better interop and have better support.

[oriolid]

The other big C# ecosystem is Unity Engine with its own frameworks and plugins. It lags a bit behind Windows, and might be one reason why some C# developers seem to be behind the times when it comes to new language features.

Edit: The other reason Unity developers are careful around new language features is avoiding memory allocations. When you write C# like it was Java it's more straightforward to see where allocations happen but it's all too easy to accidentally write allocations in your main loop if you use everything the language has to offer.