Checking out https://novadocs.panic.com/api-reference/language-client/ would help. It's the extension API documentation to connect LSP servers... but out-of-the-box JS LSP support doesn't yet exist. (Not sure about other languages though)

Edit: Python looks like LSP is working. This is a simple demo GIF: (warning - very big(23MB).) https://s5.gifyu.com/images/nova-python-demo.md.gif