Mono appears to be dead. I enjoy making life hard so I dont use windows. I am trying to learn very simple c# but am having trouble gettung visual studio to run anything on linux (debian/mint). It wont even run with dotnet in the terminal either. I dont really like all the features in vs either, i just want simple.
For reference im learning with the yellow book by rob miles. I want to learn the old way, not using a bunch of shiny helping tools (i never feel i really learn with those and it stunts my growth).
.NET/C# is fully platform agnostic and Linux is a great host system for development in C#. In fact a lot of software developed in C# (basically all of the cloud software) is hosted on Linux systems. As others pointed out Rider and VS Code are a very good choice on Linux.