I was poking around in omnisharp-emacs an hour or so ago, and found something interesting: M-x omnisharp-fix-usings. Omnisharp-emacs is a emacs package that enable you to do real .NET Core development using emacs (it might work with framework too, I’m not sure). It has code completion, shows warnings etc. Kind of like an IDE. It uses the same backend (omnisharp-roslyn) as VS Code, and most other editors use.
What the fix-usings function does is that it removes unused usings (import statements) and adds missing ones. This might be the last thing missing for me to do closer to everything in emacs at work. There will still be stuff, like legacy code bases or debugging. But I’m getting there