How to partially override nixvim for direnv flake?

[MarcusVoelker]

I've got a global configuration for my nixvim in my home manager configuration.

Now, I'd like to build project-specific versions for projects I'm managing in flakes with direnv.

Crucially, most plugins and config are supposed to be the same for all projects, it's usually just the LSP and maybe one or two specific configurations that each project needs.

Aside from it being cleaner if I don't have dependencies on, say, Haskell, globally, I also have different projects in the same language with different toolchain versions, which necessitates using different package versions in nixvim.

Is there a way to do this more gracefully than just copy-pasting the global nixvim config into each flake and then tweaking it?