@llimllib Thanks! I just added it to the quarto-nvim-kickstarter.
How did you get your tsserver to know about the Plot. methods in your screenshot?
Looks like observable themselves are building their own completion on tsserver (https://observablehq.com/blog/bringing-the-typescript-language-server-to-observable), but they do some tweaks, because observable of course comes with its own library and some syntax, not just plain javascript about which the regular tsserver will complain. But it's a great start!