Organizations have their own  convention of tagging buckets containing PII objects . We can leverage Security Posture Management to create custom rules to check if these specifically tagged buckets are open to the public:

AWS : S3Bucket where Access eq "Public" should not have Tags with [ Name eq "PII" ]

Azure: StorageAccount where ( Tags with [ Name eq "PII" ] ) should have every BlobContainers with [ Access eq "None" ] or not AllowBlobPublic

GCP: Bucket should not have Policies with [ Members . AllUsers eq True or Members . AllAuthenticatedUsers eq True ] and Tags with [ Name eq "PII" ]