Having more granular permissions has been a long standing request.
You should be aware that every collaborator in a base, even read-only collaborators have the ability to share all of the data in a base. They also have the ability to copy the entire base, including both its structure and data and keep that copy long after they are removed from the original base.
If this type of security is a high priority for you, Airtable might not be the right platform for you right now.