Different folders for npm and yarn

Question

I coded a web application for which I use yarn for managing CSS and JavaScript dependencies. I decided to start using tools like parcel, sass, typescript, etc which I added as dev dependencies in my package.json file.

The package.json file is in the root folder, but my yarn-installed dependencies are in the /public/vendor/ folder, because anything outside the /public/ folder is not directly accessible to users. So I can't link the libraries in the /node_modules/ folder to my HTML.

Here is the content of my /.yarnrc file:

--modules-folder ./public/vendor --ignore-optional --production=true

The problem is that even though yarn will create its own yarn.lock file, it takes into account the contents of the package-lock.json file. So if a dependency has already been installed by npm, it won't be installed by yarn unless I explicitly declare it to be installed (meaning it works for dependencies, but not for dependency dependencies).