Idea behind Foam is that they use GitHub and vscode features - answering on your question, I didn't find any extension with this feature.
But more interesting question, do you really need this "copy/paste" feature in your research (or just simple notes)?
This is awesome! Thank you for sharing. On the page you linked, the github link doesn't take me to the repo, just to a generic github page; you might see an increase in users if it did!
I welcome the added flexibility of this new syntax. This eases encapsulation of related logic within the same block of code, instead of having it spread over different Vue directives.
Plus, at a glance, it seems very easy to pick up and very intuitive.
I also appreciate that you stay away from "javascript classes"