For LSP:
Javascript needs some npm packages (classic):
https://github.com/ryanolsonx/vim-lsp-javascript
Python needs some pip packages (also classic):
https://github.com/prabirshrestha/vim-lsp/wiki/Servers-Python

For NeoVim setup: For dev icons needed to:
brew tap homebrew/cask-fonts
brew cask install font-hack-nerd-font
And set Hack Nerd Font in iterm2 pref