Can you code on linux using Jetbrains to create .NET 3.5 apps for a Windows target? 3.5 is just an example because the matching VisualStudio works more or less in wine, while I haven't tested 4.0 and more recent.
(Working well inside wine qualifies as popular for me)
I'd think 3.5 had a greater user base than .net core.
Edit: what I could stand to gain is that I work weekly in four or five languages. Already well tooled up in Ubuntu and vscode. Nothing frustrates me more than having to keep multiple IDEs consistent. Imagine driving two cars all day that have their controls in all different places.
You can download the SDK from https://dotnet.microsoft.com/ and use it on any platform with your editor of choice, including JetBrains Rider, which is a cross-platform .NET IDE.
.Net Core hasn't been too bad outside VS... I do wish they'd stuck to the JSON project format. I also wish dotnet had a task runner like npm in it.
Same with VS vs. VSCode - I'm happy that it works great for you, but I'm not sure why you'd think they're comparable tools.