Yes - while WPF and Windows Forms are still Windows-exclusive, there are several cross-platform UI libraries for .NET Core, like Eto.Forms (https://github.com/picoe/Eto) and Avalonia (https://avaloniaui.net/).
It's also possible to build an Electron wrapper around an ASP.NET Core web app: https://github.com/ElectronNET/Electron.NET