External collaborators permitted from specific areas

We have a need to allow external collaborators to our environment - this is currently "off" as no external collaboration is allowed currently.

Can we limit external collaborators to only certain root folders/directories or is this all or nothing?

Ideally, we have our internal directory of folders and will now have a separate directory where we will be setting up external collaborators/clients. The goal would be to ensure that we can't accidentally add an external collaborator anywhere in our internal directory.