It is possible to share buckets or files through ACLs or presigned URLs.
With ACLs you can grant permissions on specific projects or groups to perform specific actions on a bucket ('bucket ACLs') or an object ('object ACLs').
With presigned URLs (right-click on the object or left-click on its three-dot menu) anyone can access the object, until the expiration time (minutes or hours) specified by the user sharing it, even if the bucket and the object are private.
