On 23 sept 2019, Microsoft announced the release of .NET Core 3.0.
.NET Core is open source and cross-platform.  You can use .NET Core to run server applications on Windows, Mac, a dozen Linuxes, iPhone, IoT devices, and more! 

Fully supported. Open source, yes, but fully supported with the full weight of Microsoft.
It includes many improvements, including 
- Adding Windows Forms and WPF, 
- Adding new JSON APIs, 
- Support for ARM64 and improving performance across the board.
- C# 8 is also part of this release, which includes nullable, async streams, and more patterns. F# 4.7 is included, and focused on relaxing syntax and targeting .NET Standard 2.0. 
Platform support
.NET Core 3.0 is supported on the following operating systems:
- Alpine: 3.9+
- Debian: 9+
- openSUSE: 42.3+
- Fedora: 26+
- Ubuntu: 16.04+
- RHEL: 6+
- SLES: 12+
- macOS: 10.13+
- Windows Client: 7, 8.1, 10 (1607+)
- Windows Server: 2012 R2 SP1+
Windows Forms and WPF apps only work on Windows.
Chip support follows:
- x64 on Windows, macOS, and Linux
- x86 on Windows
- ARM32 on Windows and Linux
- ARM64 on Linux (kernel 4.14+)
 If you missed the .NET Conf 2019 live sessions, you can watch the full videos list at Visual Studio Channel on youtube now!
 Check also,