I don't spend much time w/ that stack, but Avalonia [1] seems to be a big player. Even better, they recently merged .Net core support [2]. You of course lose some native look and feel.
This may be too small of a place to explain it and I'm not completely familiar w/ the ecosystem, but .Net core is the .Net runtime built for cross-platform use. It doesn't have all of .Net framework, but they are adding a bit at a time. See https://www.microsoft.com/net/core/platform
1 - https://github.com/AvaloniaUI/Avalonia 2 - https://github.com/AvaloniaUI/Avalonia/issues/314#issuecomme...