Did you mean to say a debugger? That one has an open alternative (NetCoreDbg) alongside a C# extension fork which uses it (it's also what VS Codium would install). It's also what you'd use via DAP with Neovim, Emacs, etc.
Omnisharp is what the base C# extension used previously. It has been replaced by Roslyn LS (although can be switched to back still). You are talking about something you have no up-to-date knowledge of.
Did you mean to say a debugger? That one has an open alternative (NetCoreDbg) alongside a C# extension fork which uses it (it's also what VS Codium would install). It's also what you'd use via DAP with Neovim, Emacs, etc.