https://github.com/python-lsp/python-lsp-server
Rust analyzer is written in Rust, gopls in Go, clangd in C++, R language server in R, Jsonnet language server in Go, sqls in Go.
This. Learned it the hard way. For many moons, I tried integrating YouCompleteMe and the like. Then one day, I just gave up and switched to `coc.nvim`