[lennoff]

Slightly related question: is there a plug-in that can color my code based in scope instead of syntax?

[srcreigh]

There is one for emacs. Could be good inspo if someone wanted to make a VSCode version.

https://github.com/alphapapa/prism.el

[kdmytro]

Not exactly what you asked for, bun indent-rainbow colors the indentation space per nestedness level.

Also, I think the old bracket colorimg extension has an option to underline the entire section of code between the brackets pair you're currently in.