When I considered C# via Mono in 2016, it was definitely not ready for production. ASP.NET MVC, for example, would not run on it.

The state of things have probably improved with Microsoft’s investment in Linux. But I’d assume that the primary ecosystem users will make implicit assumptions about the operating system.

C# is only “kind of nice” (a better Java, before Java also became a better Java), but with JVM I can use both Clojure and/or Scala.