What about the developers tools and the developer environment? Since C# is cross-platform, it would be easy to develop software also in a UNIX-like setting, right?
It is easy. You can write C# in anything these days, Rider becoming a favorite pretty quickly for many. Everything like dotnet CLI just works on Linux too.
I'd say close to just works. I've spent the last 6 months developing with Rider on Arch and it hasn't been a completely smooth ride. Admittedly, a lot of my pain just came from inexperience. I screwed up permissions; it took me ages to setup the right .net packages due to the nomenclature (which, when I installed Visual Studio on Windows, is easily glossed over); function apps took a while to get working.
But it really is satisfying once you've got everything working.