>Can I expect non-UI .NET code to port well to Linux

If it wasn't written with tons of pinvoke to win32 or using Windows-only services (like WCF), then sure.

I've been building NET Core applications for Linux and exclusively on Linux for a few years now, mostly using Rider as the IDE. No complaints. I haven't seen any Windows-exclusive libraries worthy of any attention in all that time. Even libraries with tons of native code (like imagemagick) have Linux support.

The official MS tooling is behind what they offer on windows, but it's getting there. You can collect GC and memory dumps

https://docs.microsoft.com/en-us/dotnet/core/diagnostics/dot...

https://docs.microsoft.com/en-us/dotnet/core/diagnostics/dot...

traces:

https://docs.microsoft.com/en-us/dotnet/core/diagnostics/dot...

and here's the port of the veritable sos tool:

https://docs.microsoft.com/en-us/dotnet/core/diagnostics/dot...