As I keep having to repeat here ad-nauseam, DevKit is optional, you only really need base C# extension which is what provides language server, debugger and code completion capabilities. For VSCodium and non VSC-based distrubutions there's also a fork that packages Samsung's NetCoreDbg component instead of vsdbg.

You'd be right to point out that confusing README of these two does not do .NET any justice however.