I've been thinking about this comment for a few hours now! I love it! I like building VS Code extensions and realized quickly the benefit of writing the logic in an LSP but I would never have thought to do the SSH config thing you describe.
I've now started a Makefile lsp since you've inspired me to think about the painful scenarios that LSP can solve if I think a bit wider.
I wrote this for the infracost LSP so I could write multiple IDE extensions. Its not even really a language server, its just a neat way to parse the Terraform/Cloudformation and return diagnostics.
- Makefile: https://github.com/owenrumney/make-ls
- Goreleaser: https://github.com/owenrumney/goreleaser-ls