So you want to leverage all that goodness from web components [dot] org huh? Awesome! There's a minor thing you need to do differently from typical yarn repos you might be used to.
Because this is a monorepo and we're optimizing for file space, you need to always do installations from the monorepo (factory) root. Here's the workflow for adding elements from webcomponents.org / other npm repos
This is a little annoying (ehhh what's up doc ) for sure but VS Code plugins help ensure that you add things to the package.json of the correct version in the dependencies block. All of our element library implementations have a dependencies and devDependencies block automatically.